Dissolve the baking soda in the yoghurt. Beat the eggs with the sugar, add the yoghurt and gradually add all other products for the layer. Pour the mixture into a greased and floured tray and put to bake in the warm oven at 356°F (180 °C) for about 25 minutes.
To prepare the glaze, pour the powdered sugar and butter in a pan on the stove and stir until you get a caramel liquid. Then add the cocoa while stirring and, if necessary, dilute with a little hot water.
Allow the finished cake to cool and cut it into squares, then top with the glaze. Optionally, sprinkle coconut flakes or roll each square in them.