How to make
Heat the oven to 340°F (170 °C). Grease a baking tin with a diameter of 10″ (25 cm), and flour it. Beat the butter with sugar until it becomes a fluffy cream. Add 1 egg and vanilla essence and mix well.
Add 2 egg whites one at a time, stir well after each. Separately, sift the flour with the baking powder, baking soda and salt. Add the sifted flour to the egg mixture, alternating with the yoghurt 3 times. Dissolve the chocolate in the hot water. Add the cinnamon and sugar.
Put 1/4 of the vanilla dough in a separate bowl. Add the cocoa to it and mix well. Pour the vanilla dough into a cake form. Using a spoon, place the chocolate dough on top.
Smooth out the dark dough and using a knife, skewer, or fork make a few circular motions on top. Bake about 40-50 minutes, check its readiness with a toothpick or skewer.
Cool slightly in the form and take it out. Sprinkle with powdered sugar.
