How to make
Stir the yogurt into a bowl with the baking soda, add sugar, cocoa, flour and a little nuts if desired. You can add 1-2 tablespoons of melted chocolate.
Mix until uniform with a wooden spoon. Pour the mixture into a greased and lightly floured form. Bake the layer at 390°F (200 °C) in a heated oven for about 35 minutes or until ready.
Finally, check with a toothpick to see if it is ready.
Once ready, invert it into a tray and smear it with the chocolate, mixed with the butter and walnuts.