Pour in a bowl yogurt, 100 g ricotta cheese, milk and 2 eggs: mix all using an electric beater for 5 minutes, getting a soft cream.
Aside, in another bowl, pour flour, rice flour, sifted cocoa, baking powder and 110 g of sugar: mix everything with a whisk.
Add this mixture to the other already prepared using an electric beater.
Finally, add chopped chocolate and mix with a spatula.
Turn on the oven at 180 °C.
Grease and flour a 22 cm cake mold (or grease it and cover with baking paper) and pour in the dough.
Put in a bowl the remaining 180 g of ricotta, the remaining 40 g of sugar and the last egg: mix all with electric beater getting a smooth and soft mixture.
Pour this mixture over the chocolate dough in the mold.
Using a long spit for skewers, make circular movements in order to mix a little the white dough and the brown one.
Bake for 40-45 minutes.
Take out from the oven, let cool completely, sprinkle the cake with icing sugar and serve.