Chocolate Peanut Butter Oatmeal Muffins

In a large bowl, sift all purpose flour, cocoa powder, baking powder, baking soda, and salt. Add oats, peanut butter chips, and chocolate chips. Vigorously whisk in eggs and vanilla extract.

In the same bowl, add sugar, melted butter, and buttermilk. Stir until all large lumps are gone. Be sure not to over-mix. Cover batter and refrigerate for 4 hours or overnight.

Preheat oven to 425°F. Line a muffin pan with liners and fill with the batter 3/4 full.

Bake for 6–10 minutes. Do not open the oven door—reduce oven temperature to 350°F and bake for another 15 minutes.

Insert a toothpick into one of the muffins and make sure it comes out clean.