Fold 2 cups of chocolate chips into the thick batter using a spatula. Line a 12-cup standard muffin tin with paper muffin liners (or grease the tin cups very well with nonstick cooking spray).
Transfer the muffin pan to the middle rack of the oven and bake for 8 minutes. Then, without opening the oven door, decrease the oven temperature to 375° F (190° C) and bake for an additional 17-22 minutes.