Separate the egg whites from the yolk, beat the whites until stiff peaks are set.
Then beat the yolks, sugar and butter with a mixer until obtaining a homogeneous cream. Add the flour mixed with the chocolate, always alternating with the milk.
Then coke the bicarbonate and stir, add the baking powder and stir gently. Finally, place the egg whites and mix gently.
Place in a preheated oven at 180° and bake for about 40 minutes, or until you do the toothpick test and it comes out clean from the cake.
For the topping and stuffing: mix all the ingredients and bring to a low heat, when it starts to boil, turn off after 3 minutes. Reserve.
Cut the cake in half with the help of a knife, put the filling, then cover and add the sprinkles.