Brown the butter – Add the butter in a saucepan and melt it on medium heat. Mix the butter with a spatula until it's completely melted and comes to a boil. After a few minutes, the butter will start to foam up; keep mixing until you see streaks of brown in the foam. This means that the butter has started browning, and you will also be able to smell a nutty aroma. Once the brown streaks appear, cook for 1-2 more minutes and take it off the heat. Keep a close eye on the butter once it starts foaming, as it can burn very easily. Transfer the butter to a heat-proof bowl immediately to stop the cooking process. Let it cool to room temperature.
75 grams butter
Preheat the oven to 180 degrees Celsius. In a bowl, combine all the dry ingredients – flour, brown sugar, baking powder, and salt with a hand whisk.
250 grams all-purpose flour, 125 grams packed brown sugar, 10 grams baking powder, 1/4th tsp salt
In another bowl, whisk together milk, egg, and vanilla essence until well combined.
250 ml full-fat milk, 1 large egg, 1 tsp vanilla essence
Pour the milk mixture into the dry ingredients and whisk until everything is well combined. There might be a few visible lumps in the batter at this stage, don’t worry about it.
Finally, drizzle the melted brown butter into the cake batter while whisking it in. Keep whisking until all the butter has been added and is well incorporated into the batter.
Make the crumble: In a bowl, mix all the dry ingredients: brown sugar, flour, cinnamon powder, and salt until well combined. Cut the cold butter into small cubes and add it to the dry ingredients. Rub the mixture using your hand or a fork until the crumb reaches a wet sand-like mixture. Don't overwork the mixture; the butter will become too soft, and the crumb will not crisp up while baking.
60 grams packed brown sugar, 55 grams all-purpose flour, 2 tsp cinnamon powder, 1/2 tsp salt, 100 grams unsalted butter, cold
Transfer the batter to a cupcake tray lined with cupcake liners, filling each liner halfway through. Then, take a piping bag filled with Nutella, push it into the middle of the liner, and pipe the Nutella in. Try to keep the tip of the bag in the middle of the batter so that the Nutella does not sink to the bottom. Top with a little more batter to cover any visible Nutella spots, then sprinkle cinnamon sugar and cinnamon crumble on top. Repeat this process for each cupcake.
Cinnamon sugar, 150 grams Nutella
Bake the cupcakes for 15-20 minutes until a toothpick comes out clean from the center. Let them cool slightly before serving. You can also top them with a simple icing or cream cheese glaze.