Preheat oven to 425°F. Grease a 12 cup muffin tin with non-stick cooking spray or line with paper liners.
In a large bowl, toss together the flour, baking powder, baking soda, salt and chocolate chips. Set aside.
2 ½ cups all purpose flour, 1 tablespoon baking powder, ½ teaspoon baking soda, ½ teaspoon salt, 1 cup mini chocolate chips
In a medium bowl, whisk together the melted butter, sugar, eggs, buttermilk and vanilla.
½ cup butter, 1 cup granulated sugar, 2 large eggs, 1 cup buttermilk, 1 teaspoon vanilla extract
Slowly the wet ingredients to the dry ingredients, and stir in just until combined. Don't overmix.
Divide the batter into the prepared muffin tins, and sprinkle with coarse sugar.
Bake for 5 minutes. Then, without opening the oven, reduce the oven temperature to 375°F.
Continue to bake for another 10-15 minutes or until a toothpick inserted into the center comes out clean. Do not overbake or the muffins will be dry.
Let cool in the pan for about 5-10 minutes and enjoy warm.
Notes
Flour: To properly measure the flour, weigh it (click "metric" just above the recipe for the weights) or sift/stir it to break it up, lightly spoon into the measuring cup, and level without packing.
Chocolate chips: I like to use mini chocolate chips so that there are little bites of chocolate in each bite. You can use regular semisweet chocolate chips if you prefer.
Coarse sugar: The coarse sugar adds a sweet crunchy crust to to the muffins and that bakery-style look. You can omit it if you prefer.