Ghirardelli Double Chocolate Muffins

Step 1
Preheat the oven to 350 degrees F (175 degrees C). Grease a 12-cup muffin tin with cooking spray, wiping off any excess from the top of the tin.

Step 2
Whisk flour, cocoa, baking powder, salt, and baking soda together in a bowl.

Step 3
Beat eggs and egg yolk in a stand mixer fitted with the whisk attachment on medium-high speed. Slowly stream in white sugar while beating; continue to beat, scraping down the sides and whisk as needed, until mixture is pale and thick, and ribbons come down from the whisk attachment when lifted.

Step 4
Beat in oil, then sour cream and vanilla until fully incorporated. Fold in flour mixture until only a few visible streaks remain. Fold in 3/4 of the chocolate chips. Spoon batter into the prepared muffin cups, smoothing the tops if needed but keeping them mounded slightly. Sprinkle remaining chips over top and sprinkle with coarse sugar.

Step 5
Bake in the preheated oven until a toothpick inserted into the center comes out free of wet batter (it may come out with melted chocolate), 15 to 20 minutes. Let cool in the pan for 15 minutes, then transfer to a wire rack to cool completely.