Mix the flour, sugar, baking powder, salt and cocoa powder in a bowl. Then add oil, yoghurt and espresso powder dissolved in a little water. Stir the dough until creamy for about 2 minutes. Then use two spoons to fill the dough into prepared muffin cups.
Bake the muffins at 175 ° C top / bottom heat in the preheated oven for at least 20 minutes on the middle rack.