How to cook
All of the products need to be at room temperature. Sieve the flour and baking powder, in order to allow more air in and have the dough become fluffier.
In a deep bowl, whisk the eggs and sugar into a mixture- it should become foamy and acquire a light yellow color. Slowly and gradually, add the oil while you keep mixing. Then add the milk in a trickle.
Add the flour spoon by spoon and don't stop stirring. Finally, chop the chocolate into cubes and add it to the mixture. Stir with a spatula instead of a mixer or whisk because the dough might crumble otherwise. Do not over mix!
With the prepared mixture, fill muffin cups, although you can also use a cake or pie form that you have pre-greased. Pour the mixture in carefully, not all the way up to the rim but only up to 2/3 of its volume at most. Bake in a preheated 356°F (180 °C) oven without using the fan for about 15-20 minutes.
To check if the muffins are fully baked, poke them in the middle with a toothpick. If the toothpick comes out clean - they are ready.