In a saucepan, heat the milk then remove from the heat.Add the lemon juice, mix then let stand for 10 minutes. Preheat your oven to 200°C.
In a bowl, mix all the dry ingredients: flour, cocoa, sugar, brown sugar and yeast.
Gently melt the butter with the dark chocolate then let it sit at room temperature for a few moments.
In another bowl, mix the eggs, vanilla then the melted butter and milk.
Gradually pour this liquid mixture into the dry ingredients.The dough is liquid, this is normal. Add the chocolate chips then divide the dough into baking paper cases, placed in muffin molds.
Bake for 18 minutes.
