Step 1

Preheat oven to 375°F. Spray 24-cup mini-muffin pan with nonstick spray.

Step 2

Whisk together yogurt, milk, and egg in large bowl. Add oats, brown sugar, banana, and vanilla, whisking to combine; let stand 5 minutes.

Step 3

Meanwhile, whisk together all-purpose flour, whole-wheat flour, baking powder, baking soda, and salt in medium bowl. Add flour mixture and all but 1 tablespoon chocolate chips to yogurt mixture, stirring until moistened.

Step 4

Spoon batter evenly into prepared muffin cups; sprinkle evenly with reserved chocolate chips.

Step 5

Bake until golden brown on top and toothpick inserted into center of muffin comes out clean, 15–17 minutes. Let cool in pan on wire rack 5 minutes; run knife around inside of cups to loosen muffins from pan. Remove from pan and cool completely on rack. Store in airtight container at room temperature up to 2 days or freeze up to 3 months.

Step 6

Serving size: 1 muffin