Preparation

• Combine flour, granulated sugar, baking powder, baking soda, salt and spice (if you're using it) in a medium bowl and whisk until evenly blended.
• Mash the banana well with a fork until very smooth and add it to a large bowl. Add brown sugar and eggs and whisk until glossy and smooth. Add sour cream or yogurt, oil and vanilla and whisk until combined.
• Add the dry ingredients all at once to the banana mixture and fold them in gently with a wooden spoon or a spatula until just combined. Do not over-mix. A few small lumps are just fine. Add the chocolate chips and fold them through the batter.
• Cover the bowl and set aside at room temperature for 20-30 minutes.
• Meanwhile, preheat your oven to 425°F and line the cups of a standard 12-cup muffin pan with paper liners.
• Divide batter evenly among prepared muffin cups using a 2 oz scoop, filling them to the rim. Sprinkle a few extra chocolate chips on top.
• Bake for 5 minutes, then with the oven door still closed, reduce temperature to 350°F and bake for another 13-15 minutes until golden brown and slightly firm to the touch.
• Transfer pan to a wire rack and let muffins cool for 5 minutes before transferring individually to the rack to finish cooling.