Add the eggs, sugar, and salt to a bowl. If you have a stand mixer, use the whisk attachment and whisk until everything is well combined. If not, use a hand whisk.
In another bowl, mix the warm milk with the instant yeast. Ensure the milk isn’t too hot, as that can kill the yeast. Pour the milk mixture into the eggs and whisk until blended.
Next, add the melted butter and whisk again. Then add half the flour and mix until you get a thick, batter-like consistency.
Add the remaining flour and switch to the dough attachment (if using a stand mixer). Knead on medium speed for 5-10 minutes until the dough forms a soft ball and starts climbing the dough hook. If you’re not using a stand mixer, knead by hand for 10-15 minutes until the dough is smooth and forms a ball.
Place the dough ball in an oiled bowl, cover with cling wrap, and let it rise in the fridge for about three hours, or until it doubles in size. You can also let it rest overnight for 12-16 hours.
Once risen, transfer the dough to a floured surface and knead for 2-3 minutes until smooth. Roll the dough to a thickness of 1.5 cm, making sure it’s even throughout.
Flour a cookie cutter and cut out circles from the dough, placing them on pieces of baking paper. If you want to make classic doughnuts with a hole, use a smaller cookie cutter or the back of a large frosting tip to cut out the center. Tip: Cut the baking paper into small squares and place each doughnut on a piece to make it easier to transfer them into the frying pan.
Cover the doughnuts loosely with a towel or cling film and let them rise in a warm place until they double in size. Meanwhile, heat the oil to 170 degrees Celsius.
When the doughnuts have risen and the oil is hot, fry them for about 3 minutes on each side until golden brown. To check if they are cooked through, poke one with a toothpick or small knife—it should come out clean.
Make the dusting: mix brown sugar, white sugar, and cardamom powder in a bowl.
Transfer the doughnuts to paper towels to absorb the excess oil, and while they are still hot, roll them in cinnamon sugar.
Once the doughnuts have completely cooled down, use a smalll knife to poke a hole in the center of the doughnut and fill with the rabdi inside using a piping bag and enjoy.