Step 1

Preheat oven to 425°F. Grease 14 standard (2½-inch) muffin cups with nonstick cooking spray.

Step 2

Whisk buttermilk, eggs, oil, and vanilla extract together in large mixing bowl until well-combined.

Step 3

Stir in carrot until combined.

Step 4

Add all-purpose flour, whole wheat flour, oats, granulated sugar, brown sugar, baking powder, cinnamon, baking soda and salt; stir just until combined. Don't overmix.

Step 5

Spoon batter evenly into prepared muffin tin cups.

Step 6

Sprinkle with coarse sugar, if using.

Step 7

Bake 5 minutes.

Step 8

Without removing the muffins, decrease oven temperature to 350F and continue baking for 15-20 minutes or until the muffins spring back when lightly pressed or a toothpick inserted into centers comes out clean.

Step 9

Cool in the pan for 5 minutes.

Step 10

Remove to a wire rack to finish cooling.