For the marble cakes, mix all dry ingredients (except cocoa). Mix the egg yolks and curd and add a dash of water.
Divide the mixture in half and mix one part with the cocoa powder. Beat egg whites until stiff and mix half into the light batter and half into the dark batter.
Pour the dark and light mixture alternately into small silicone molds and stir a little. Be careful not to fill the cups completely, but only 2/3 full.
Bake at 170 °C for about 30 minutes.