1. In a large bowl, beat the eggs and sugar vigorously until the mixture takes on a whitish color. Add the natural yogurt and mix. Add the dry ingredients (flour + chemical booster) to the preparation and mix. Add the melted butter.
2. Divide the dough into two different bowls. In one of them, add the cocoa powder and mix well.
3. In the other bowl, add the vanilla and mix well.
4. Pour the two masses into the muffin tin, alternating with a tablespoon.
5. Once all the dough has been poured into the mold, mix the two masses a little with a wooden skewer or the tip of a knife, without using too much so that they do not collapse.
6. In the oven preheated to 180°C, we bake our muffins for 15 minutes.
7. Once cooked, let them cool completely (preferably on a rack).