Preheat your oven to 425 degrees and prepare your muffin tin with liners, or grease it well with non-stick cooking spray.

Dry Ingredients: In a large bowl, combine the flour, baking powder, baking soda, salt, and chocolate chips and set it aside.

Wet ingredients: In another bowl, mix together the melted butter, sugar, eggs, buttermilk, and vanilla.

Combine: Add the dry ingredients to the wet mixture and use a spatula to gently fold the mixture together, just until combined. Be careful not to over-mix the batter.

Bake: Divide the batter evenly among well-greased muffin cups (they will be full to the top). Bake at 425 degrees F for 5 minutes. Then, reduce the oven temperature to 375 degrees F and continue baking for 10-15 more minutes or until a toothpick inserted into the center of a muffin comes out clean. Don't over-bake them or they will be dry.

Remove muffins to a wire cooling rack to cool.