How to make
Dissolve the baking soda in the yoghurt until effervescent. In a bowl, add the yoghurt and beat it with the egg and sugar. Whip until the sugar melts and add the oil, raisins and walnuts. Finally, mix well with 2 cups of flour, cocoa, baking powder and cognac.
Pour the mixture into a greased and lightly floured tray and put it to bake in a moderately heated oven for about 40 minutes. Cut the cake into squares or diamonds while still warm. For the glaze, melt the butter with the sugar, cocoa and top it up with cognac.
Stir for 30 seconds and remove it from the heat. Top the cooled cake with the glaze and place it in the refrigerator for several hours before serving.
Garnish with ground nuts or coconut flakes.