- 4 (1 1/2 to 2 pounds) ripe bananas, plus 1 for garnish (more if making mini muffins)
- 1 cup packed light-brown sugar
- 1/2 cup canola oil
- 1 large egg
- 1 cup all-purpose flour
- 1 cup whole-wheat flour
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 cup sour cream
- 1 tablespoon pure vanilla extract
Preheat oven to 350 degrees. Line a muffin pan, regular or mini, with paper liners.
Peel four bananas, and place them in the bowl of a mixer fitted with the paddle attachment. Beat until mashed, about 1 minute. Add brown sugar, oil, and egg; beat until smooth. Reduce speed to low. Add flours, baking powder, baking soda, and salt; beat until smooth. Add sour cream and vanilla; beat until combined.
Fill muffin liners three-quarters full. Slice remaining banana into 1/8-inch-thick rounds; place a slice on each muffin. Bake until tester inserted into center comes out clean, about 25 minutes for regular muffins and 20 for mini, rotating pan halfway through. Transfer to wire rack to cool. Store, covered, at room temperature.