Makes 12 muffins

Ingredients

½ cup (1 stick) unsalted butter, melted and cooled
2 large eggs
1 cup low fat buttermilk
2 teaspoons pure vanilla extract
1 ¾ cups all-purpose flour
⅔ cup unsweetened cocoa powder (not Dutch processed)
1 ¼ cups light brown sugar (be sure it is fresh with no hard lumps)
1 teaspoon baking powder
1 teaspoon baking soda
½ teaspoon salt
¾ - 1 cup (to taste) semi-sweet or bittersweet chocolate chips (I like Ghirardelli)

Directions

1. Position rack in center of oven and preheat 425 degrees. Spray a standard 12-cup muffin pan with nonstick cooking spray, then line with paper liners.

2. In a large measuring cup or bowl, whisk together the eggs, buttermilk, and vanilla extract.  In another large bowl, whisk together the flour, cocoa powder, brown sugar, baking powder, baking soda, and salt. Stir in the chocolate chips. Add the wet ingredients and the melted butter to the dry ingredients and fold together with a rubber spatula until just combined. Do not over-mix the batter or the muffins will be tough (it's okay if there are still a few specks of the dry mixture).

3. Using an ice cream scoop or two spoons, fill the muffin cups to the brim with batter. Place in the oven and bake for 8 minutes, then turn oven down to 350 degrees and bake for about 12 minutes more, or until a toothpick inserted in the center of a muffin comes out clean (check a few spots as the melted chocolate chips will make the tester look wet). Transfer to a wire rack and let cool for about 5 minutes before removing muffins from pan; cool on rack.