Preheat oven to 375°F. Spray 24-cup mini-muffin pan with nonstick spray.
Whisk together yogurt, milk, and egg in large bowl. Add oats, brown sugar, banana, and vanilla, whisking to combine; let stand 5 minutes.
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.
Spoon batter evenly into prepared muffin cups; sprinkle evenly with reserved chocolate chips.
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.
Notes
3 WW PointsServing Size: 1 Muffin
Tips and Tricks
Mixing Batter Stir the batter just until mixed to keep the muffins soft.Banana Ripeness Use bananas with plenty of brown spots for better sweetness.Chocolate Chips Mini chips spread more evenly than regular chips.