Step 1

Preheat the oven to 350°F and set an oven rack in the middle position. Spray a 12-cup muffin pan with nonstick cooking spray.

Step 2

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

Step 3

In a large bowl, whisk together the melted butter, granulated sugar, brown sugar, and vanilla. Whisk in the eggs, followed by the sour cream. Add the dry ingredients and whisk until evenly combined. Stir in ⅔ cup of the chocolate chips.

Step 4

Spoon the batter evenly into the prepared pan, filling the muffin cups about three-quarters full. Sprinkle the tops with the remaining chocolate chips, followed by the coarse sugar. Bake for 18 to 20 minutes, until domed and golden brown. Let the muffins cool in the pan for about 10 minutes, then transfer to a rack to cool completely. The muffins are best enjoyed fresh on the same day, but leftovers will keep well in a covered container for a few days. (To refresh individual muffins, warm in the microwave for 15 to 20 seconds.)

Step 5

Freezer-Friendly Instructions: The muffins can be frozen in an airtight container or sealable plastic bag for up to 3 months. Thaw for 3 to 4 hours on the countertop before serving. To reheat, wrap individual muffins in aluminum foil and place in a preheated 350°F oven until warm.