Instructions

• Preheat oven to 350°F and place the oven rack in the center position. Spray a 12-cup regular muffin pan (and an optional mini loaf pan, if using) very well with floured cooking spray or grease and lightly flour the pan; set aside. (This recipe yields about 13–14 muffins, or one dozen plus one mini loaf — discard excess batter if you are not using a mini loaf pan.)
• In a large bowl, whisk together 1 ½ cups all-purpose flour, 1 cup granulated sugar, ¼ cup unsweetened natural cocoa powder, 1 teaspoon baking soda, ¼ teaspoon baking powder, and a pinch of salt (optional); set the dry mixture aside.
• In a medium bowl, whisk 1 large egg, ⅓ cup canola or vegetable oil, ¼ cup sour cream (or Greek yogurt), and 1 tablespoon vanilla extract until combined.
• Stir 1 ½ cups mashed ripe bananas into the wet mixture until evenly mixed.
• Pour the wet ingredients into the dry ingredients and gently stir with a spatula or spoon until just combined. Scrape the bottom of the bowl to incorporate any dry bits; do not overmix.
• Fold in 1 cup mini semi‑sweet chocolate chips until evenly distributed.
• Using a large cookie scoop, 1/4‑cup measure, or spoon, divide the batter among the prepared muffin cups, filling each about 3/4 full. If using a mini loaf pan, fill it with remaining batter; otherwise discard any excess.
• Sprinkle about 1 teaspoon granulated sugar on top of each muffin.
• Bake at 350°F for 22–25 minutes, beginning to check at 20 minutes. Muffins are done when they are set, domed, springy to the touch, and a toothpick inserted into a crack comes out clean or with a few moist crumbs (melted chocolate chips can look like wet batter—do not confuse them with uncooked batter).
• Remove the pan from the oven and let the muffins cool in the pan for about 10–15 minutes, until firm enough to handle.
• Transfer muffins to a wire rack to cool completely.