Preheat the oven to 180 ° C (convection). Mix the yogurt, oil, sugar and vanilla sugar together thoroughly. Add the two eggs and stir together.
Briefly stir in the flour, baking powder and cocoa powder. If the mass is too firm, you can add some of the cherry juice. Finally, carefully fold in the chocolate chips and sour cherries.
Pour the batter into the muffin molds, fill a maximum of 3/4. Bake at 180 ° C (fan oven) for 20-25 minutes, depending on the oven. Then the muffins are crispy on the outside and juicy and fluffy on the inside.