Preheat oven to 180°C / 350°F.
Mix flour, cocoa powder, baking powder, baking soda, salt, and sugar.
In another bowl, whisk eggs, milk, oil, and vanilla.
Add the wet ingredients to the dry ingredients and mix gently.
Stir in the chocolate chips, then slowly add hot water or coffee. Don't overmix.
Fill muffin cups about ¾ full and sprinkle extra chocolate chips on top.
Bake for 18–22 minutes, until a toothpick comes out with a few moist crumbs.
Cool slightly and enjoy warm.
