Preheat your oven to 425°F (220°C) and line a muffin tin with paper liners or grease it lightly.
In a large mixing bowl, combine the all-purpose flour, unsweetened cocoa powder, baking powder, salt, and chocolate chips. Mix well to guarantee even distribution of the dry ingredients.
In another bowl, whisk together the melted chocolate, vegetable oil, sugar, eggs, milk, and vanilla extract until the mixture is smooth and well combined.
Gradually add the wet mixture to the dry ingredients, stirring gently until just combined. Be careful not to overmix; a few lumps are okay.
Divide the batter evenly among the muffin cups, filling each about ¾ full. Bake in the preheated oven for 5 minutes, then reduce the temperature to 375°F (190°C) and continue baking for an additional 12-15 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
Allow the muffins to cool in the tin for about 10 minutes before transferring them to a wire rack to cool completely.
For the best results, make sure to measure your ingredients accurately and avoid overmixing the batter to keep your muffins light and fluffy.
