Put the flour, cocoa, baking powder, baking soda and salt in a bowl. Mix gently.
In another bowl put the liquid ingredients: beaten eggs , milk , oil and vanilla essence.
Pour the liquid slowly over the flour mixture.
Mix only enough to incorporate.
Place muffin papers in form and pour the composition.
Bake for about 25 minutes or until you put a toothpick in and it comes out clean.
You can put raisins soaked in rum in the composition, or raspberries, blueberries, nuts, etc.