Preheat oven to 170°Celsius. Grease muffin pans or use paper liners. In a bowl, mix together the flour, cocoa powder, baking powder and salt; set aside.

In a large bowl, whisk the sugar, egg, and vegetable oil. Add and mix the yogurt and water. Fold in the mixed dry ingredients. Scoop into muffin pans.

Bake in preheated oven for 15-20 minutes or until inserted toothpick comes out clean.