Made with the infamous butter biscuits, this mousse cake with layers of a tres leches-soaked sponge, caramel sauce, peanut praline, and butter biscuit mousse will make sure that your biscuit box is NOT filled with sewing material (for once!).
No matter where you’re from, we’ve all had one shared cultural “experience” (*cough, trauma*), the betrayal of the blue biscuit box. I think we can all remember the moment when we were little kids and came across that glorious, shining box of butter biscuits, and opened it to find…sewing material. THIS IS WHERE OUR TRUST ISSUES STARTED.
But today, I am here to undo that trauma by giving you a blue biscuit box that’s NOT filled with sewing material but something even better than the original biscuits—a layered butter biscuit mousse cake with a light sponge cake at the base soaked with a tres leches mixture, topped with salted caramel sauce and praline, and a creamy, no-egg, no-gelatin butter biscuit mousse, finished with a layer of your favorite butter biscuits on top.
It’s like a box of nostalgia, and it tastes absolutely delicious.
Let’s get into the details of the recipe.
Tres Leches Cake Base
The first layer of this mousse cake is a tres-leches-soaked sponge. Tres Leches is a Mexican-origin cake made with a super light and airy sponge soaked with a mixture of three kinds of milk – condensed milk, evaporated milk, and heavy cream (hence the name).
The milk cake stays soft, flavorful, and spongy underneath all the layers and makes for the perfect flavor and textural addition to the mousse cake, and it’s super simple to make.
Here are the steps for making the Tres Leches Cake.
- Separate the egg whites and yolks in two separate bowls.
- Add half the sugar in each bowl, and whip the egg whites until they’re doubled and frothy and the egg yolks are pale and creamy.
- Fold the egg whites and flour into the egg yolks with a spatula in three intervals, alternating after each addition. Make sure not to rush the process, you want the batter to be as airy as possible so that the cake is light and spongey.
- Pour the cake batter into a cake pan that’s the same size as your biscuit tin and bake for 10-15 minutes. The cake layer should be quite thin, around 1-1.5 inches only to create the right balance in the mousse cake.
- While the cake bakes, make the three-milk mixture by mixing the condensed milk, evaporated milk, and heavy cream (or liquid whipping cream) until combined.
- Place the baked cake into the cookie tin (that you will be assembling the mousse cake in), poke holes into it using a fork, pour the milk mixture on top, and let it soak. It is important to soak the cake only AFTER placing it into the tin as the cake will become very soft once it has been soaked and may become difficult to move.
Salted Caramel Sauce
The biscuit mousse on itself would taste very flat and kinda bland, so I’ve paired it with salted caramel sauce that perfectly balances the sweetness of the mousse with a salty, rich flavor.
You could use store-bought caramel sauce but I HIGHLY recommend making your own, the difference is well worth it!
And if you’re intimidated by caramel, I have a simple and fool-proof recipe you can follow to make the most delicious salted caramel sauce.
Here are the steps for making the salted caramel sauce.
- Add sugar and water to a saucepan without stirring. Important: Don’t use a spoon to mix, as this can cause crystallization. Instead, gently swirl the pan to ensure all sugar is covered with water.
- Place the saucepan over medium heat and let it cook, swirling every few minutes to help the sugar dissolve evenly.
- To avoid a grainy texture, use a damp pastry brush to wipe down any sugar crystals on the sides of the pan.
- Once the sugar reaches a medium-dark amber color, carefully add the warmed cream and whisk until fully combined.
- Cook for another 1–2 minutes, then add the butter, whisking until smooth. Cook for one more minute. Remove from heat, add salt, and stir to combine.
- After it cools slightly, blend the caramel with a stick blender or regular blender to emulsify the butter and create a smooth, glossy sauce.
- Storage Tip: Caramel can be made a day ahead and stored in an airtight container until needed.
Peanut Praline
This peanut praline is addicting-ly delicious on its own, but when paired with the creamy biscuit mousse, it tastes even better! The crunchiness of the praline adds the perfect texture to the cake and takes it to a whole new level.
The best part? All you need is three ingredients – water, caster sugar, and peanuts.
Here are the steps for making the peanut praline.
- Dry roast your peanuts until they’re nice and brown, then set them aside.
- In a saucepan, add the water and caster sugar. Make sure not to mix it, and cook on medium heat until all the sugar is dissolved.
- Add the peanuts to the sugar syrup and mix continuously. Initially, the sugar will crystalize around the peanuts, but don’t panic! Keep mixing and in 5-7 minutes, the sugar will completely melt and form an amber coating on the peanuts.
- Cook only until the sugar is melted, or it may burn. As soon as it’s done, pour the caramelized nuts on a baking sheet. Let them set for 30 minutes until they are hard, then break them into smaller pieces.
- This praline can be stored in an airtight jar for up to a week, it’s also great for snacking!
Butter Biscuit Mousse
Now for the star of the show. This white chocolate-based mousse is super simple to make, and uses no gelatine or eggs. All you need is white chocolate, milk, liquid whipping cream, and of course, the butter biscuits.
Here are the steps for making the butter biscuit mousse.
- In a saucepan, place the milk, cream, and butter biscuits. I recommend using the two plain kinds that are available in every butter cookie box (vanilla ring and country style) so that the taste remains original. Some of the other biscuits have flavors like coconut, so I recommend you do not use those.
- Cook the mixture on low heat for 5 minutes, letting the biscuit simmer in the milk mixture. After 5 minutes, the biscuits will become soft and you can easily break them down using a spoon. Continue doing so until the biscuits have completely melted into the milk mixture and there are no lumps. The mixture will resemble weird baby food but don’t worry about it.
- Take it off the heat and add the white chocolate to the biscuit mixture. Let it sit for a minute, allowing the white chocolate to melt, then whisk until the chocolate is fully melted and combined. The mixture will now look like a smooth, thick ganache. Set it aside until it cools down.
- Meanwhile, whip the remaining cream to medium peaks. Make sure not to overmix at this step as it has to be further whipped with the biscuit ganache and it may split.
- Once the ganache has cooled down, add it to the cream and fold it in gently with a spatula until fully combined. Make sure the ganache is not warm or the cream will melt.
- Assembly: To assemble the mousse cake, pour a layer of the salted caramel sauce on top of the tres leches cake, then sprinkle some praline on top. Do not add too much praline or it will overpower the whole cake, just scatter it around. Add the prepared mousse on top, smooth it out, then chill the cake in the fridge for at least 4 hours so that it sets properly.
- Before serving, top the cake with butter biscuits, making it look like an actual box of biscuits on the inside. Cover the lid and surprise your guests!
This may seem like a LOT but honestly, each of the layers is so, so easy. Plus, the caramel sauce and praline can be made a couple of days in advance, and the whole cake has to be assembled a day before any event!
Ready to get started? Let’s go!
PS: I always measure ingredients in grams, never in cups. Using a measuring scale is the only way to bake accurately. Cups are very unreliable and can give different measurements, so I would suggest you buy a measuring scale before you start baking! If you can’t get your hands on one, you can use the online tools for converting grams into cups; however, I do not guarantee their accuracy.
Butter Biscuit Mousse Cake
Equipment
- Electric or hand whisk
- silicon spatula
- 7" cake pan or cake pan the same size as your cookie tin
- Saucepan for caramel and praline
- Baking paper
Ingredients
Tres Leches Cake Layer
- 2 eggs whites and yolks separated
- 35 grams white granulated sugar
- 40 grams all-purpose flour
- 40 ml liquid whipping cream
- 70 ml condensed milk
- 25 ml evaporated milk
Salted Caramel Sauce
- 25 ml water
- 100 grams white granulated sugar
- 90 ml liquid whipping cream
- 25 grams unsalted butter
- 1/2 tsp sea salt
Peanut Praline
- 115 grams caster or granulated white sugar
- 35 grams water
- 85 grams whole peanuts unsalted
Butter Biscuit Mousse
- 150 grams white chocolate
- 100 ml full-fat milk
- 80 ml liquid whipping cream
- 100 grams butter biscuits use only the two plain kind – vanilla rings and country style
- 200 ml liquid whipping cream for whipping
- More butter biscuits for topping
Instructions
Tres Leches Cake Layer
- Begin by separating the egg whites and yolks into two separate bowls.
- Add half the sugar to each bowl. Whisk the egg whites until they double in volume and look frothy, and whip the yolks until they turn a pale yellow and have a creamy texture.
- Gently fold the whipped egg whites and flour into the egg yolk mixture in three intervals, alternating each time to keep the batter as light and airy as possible—this is key for a soft, spongey cake.
- Pour the batter into a cake pan that matches the size of your biscuit tin. Bake for about 10-15 minutes; this layer should be thin, around 1-1.5 inches, so it complements the mousse perfectly without overpowering it.
- While the cake is baking, mix the three types of milk—condensed milk, evaporated milk, and heavy cream—until well combined.
- Once baked, place the cake layer into the biscuit tin. Poke holes with a fork and pour the milk mixture over the cake, letting it soak in. Tip: It’s best to soak the cake once it’s in the tin; the cake becomes delicate once soaked and might be tricky to move.
Salted Caramel Sauce
- In a saucepan, combine sugar and water. Important: Avoid using a spoon to stir, as it can lead to crystallization. Instead, gently swirl the pan to ensure all the sugar is covered.
- Set the pan over medium heat, swirling every few minutes to help the sugar dissolve and caramelize evenly.
- If crystals form on the sides of the pan, brush them away with a damp pastry brush to keep the caramel smooth.
- Once the caramel reaches a medium-dark amber, carefully pour in the warmed cream (it will bubble up) and whisk until fully combined.
- Add the butter and cook for another 1-2 minutes while whisking. Remove from the heat, add a pinch of salt, and give it a final stir.
- Let it cool slightly, then blend with a stick blender or regular blender to fully emulsify the butter and achieve a silky, glossy sauce.
Peanut Praline
- Dry roast the peanuts until golden brown, then set them aside.
- In a saucepan, cook the water and caster sugar on medium heat, without stirring, until the sugar dissolves.
- Add the roasted peanuts and keep stirring. At first, the sugar will crystallize around the peanuts, but don’t worry—keep stirring, and within 5-7 minutes, the sugar will melt again, coating the peanuts in a caramelized layer.
- Be careful not to overcook, as this can lead to burning. Once the caramel forms, pour the peanuts onto a baking sheet and let them cool for 30 minutes until hardened. Then, break them into smaller pieces for easy sprinkling.
Butter Biscuit Mousse
- Combine milk, cream, and butter biscuits in a saucepan. I recommend using the two plain biscuit types from the butter cookie tin (vanilla ring and country-style), avoiding flavored ones for a more classic taste.
- Cook on low heat for 5 minutes, allowing the biscuits to soften in the milk mixture. Use a spoon to break down the biscuits until there are no lumps left and the mixture becomes smooth (it might look odd but don’t worry).
- Remove from heat and add the white chocolate. Let it sit for a minute to melt, then whisk until it turns into a smooth, thick ganache.
- While it cools, whip the remaining cream to medium peaks—don’t overmix, as it still needs to be folded with the biscuit ganache.
- Once the ganache has cooled, fold it gently into the whipped cream with a spatula. Tip: Make sure the ganache isn’t warm; otherwise, it could melt the whipped cream.
Assembly
- Place the tres leches cake layer in your tin and pour a layer of salted caramel sauce on top.
- Sprinkle the peanut praline over the caramel, keeping it light so it doesn’t overpower the cake.
- Spread the butter biscuit mousse on top, smoothing it out evenly.
- Chill the cake in the fridge for at least 4 hours to let the layers set perfectly.
- Before serving, top the cake with butter biscuits arranged to resemble the original look of the tin, close the lid, and get ready to surprise your guests!
Notes
- This cake can be stored in the fridge for 2-3 days.
- The salted caramel sauce can be stored in an airtight container in the fridge for up to a week
- The praline can be stored in an airtight container for up to a week.
- The salted caramel sauce and praline can be made a day before assembly, and the cake can be assembled a night before serving.
- Bake the cake in the same sized pan as your cookie tin to make the assembly process easier.
- Do not pour the milk over the cake before you place it in the cookie tin as the cake will become too soft to move once soaked.
- Caramel Sauce: do not stir the water and sugar before it caramelizes or the mixture will crystalize.
- Praline: As soon as the praline reaches the golden-amber stage, immediately take it off the heat and pour it on a baking sheet or it may burn.
- Mousse: do not whip the cream completely in the first whipping step or it will split when you mix it again.
- When mixing the biscuit ganache into the whipping cream, make sure the ganache is not warm or the cream will melt. Also, fold the ganache into the whipping cream gently so that the mousse remains ary and fluffy
This is one of those cakes that looks fancy, but really isn’t hard to make, and tastes absolutely delicious. The added element of making it in a biscuit tin makes it such a fun addition to your dinner table, and even a great gift!
If you give this recipe a try, don’t forget to let me know how you liked it in the comments. And of course, share it with me on Instagram!
Until next time.
