1. Preheat the oven to 180° up and down.
2. In a bowl, mix the whipped butter (slightly melted) with the sugar.
3. When the mixture is well mixed, add 3 egg yolks (save the whites) and mix with a whisk until well combined.
4. Add the milk and mix with a whisk.
5. When everything is well combined, gradually add the dry ingredients: flour and yeast. Mix everything with a whisk until there are no lumps.
6. In another bowl, beat the egg whites until stiff with a whisk.
7. Once the egg whites are beaten, gradually add the meringue to the mixture, gently mixing with a spatula until everything is well combined.
8. Divide the dough into two containers. Put 1/3 of the mixture in the container, add a spoonful of cocoa and mix well.
9. In a previously buttered and floured form, prepare a “sandwich” of dough. Pour the first layer of white dough, then add the entire cocoa dough and finally cover it with the rest of the white dough.
10. Put the heated form in for 50 minutes (without opening the oven door). Then stick a needle into the center of the dough and check if the dough is ready.
