Marbled sponge cake

Ingredients:

3 eggs L, (large), or 4 M, (medium).
1 lemon yoghurt
1 measure sunflower oil, (with the pot of yoghurt)
2 measures sugar
3 measures yoghurt, flour
1 sachet of Royal baking powder
2 tablespoons of cocoa powder
Butter to grease the mould.

Preparation:

1. In a large bowl, add the three eggs, the lemon yoghurt, one part sunflower oil (with the pot of yoghurt), two parts sugar and 1 sachet of baking powder. Beat everything with a mixer and now add 3 measures of yogurt, flour; incorporating them one by one.
2. In another bowl, pour half of the batter (I like to leave more white). Add a few tablespoons of cocoa powder and mix well.
3. Now, using paper towels, grease the cake tin or baking dish of your choice and dust with flour. Flip to remove excess.
4. Add the white mixture, then the cocoa mixture, I usually make several thin layers, always pouring in the center, one on top of the other.
5. Preheat the oven to 180º, with heat from top to bottom, and cook for about 45 minutes. Check that it is well done by pricking with a long toothpick or a skewer in the center and checking that it comes out clean.
6. Leave to cool and unmold. Take advantage now!