First mix the flour, baking powder, sugar and salt. Then mix the milk, eggs and butter together and add to the flour mixture. Mix everything thoroughly and divide into two parts. Stir the cocoa powder and Nutella under half of the batter, and the grated lemon zest under the second part. Now fill the two types of dough into the small waffle cups to just below the rim and place on a baking sheet lined with baking paper.
Put in the hot oven and bake on the lowest rack for about 15 minutes, then remove from the oven and let cool down.
However, the small muffins taste best warm.
Tip: As a modification, you can stir any ingredient into the dough, such as nuts, dried fruits, chocolate flakes, etc.
If you get the waffle cups without chocolate, you can also bake hearty muffins, e.g. with bacon and onions or pieces of salami.