Nonstick cooking spray
1 1/4 cups all-purpose flour (spooned and leveled)
1/2 cup packed dark-brown sugar
1/2 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon ground nutmeg
1/2 teaspoon coarse salt
1 cup old-fashioned rolled oats
1/2 cup raisins
3 tablespoons extra-virgin olive oil
1 large egg
1/3 cup skim milk
Preheat oven to 400 degrees. Coat a 12-cup muffin pan with cooking spray. In a large bowl, whisk together flour, brown sugar, baking soda, baking powder, nutmeg, and salt until there are no lumps. Stir in oats and raisins. Add oil, egg, milk, carrots, and banana and stir until blended.
Fill each muffin cup with 1/4 cup batter. Bake until a toothpick inserted in center of a muffin comes out clean, 23 to 25 minutes. Serve muffins warm or at room temperature.