First, mash the bananas with the sour cream and vanilla.

In a medium bowl, use a fork to mash the bananas, adding the sour cream and vanilla and stirring them into the mixture.

Mix the dry ingredients.

In another medium bowl, whisk together the flour, baking soda, baking powder, and salt.

Beat the sugar and butter, then add the eggs.

In the bowl of a stand mixer fitted with the paddle attachment, combine the brown sugar and butter.

Beat on medium-high until light, fluffy, and doubled in volume, 2 to 3 minutes.

Reduce the mixer to low and add the eggs one at a time.

Alternate adding the dry ingredients with the banana mixture.

With the mixer still on low, add the dry ingredients in two equal parts, alternating with the banana mixture in two equal parts.

Scrape down the bottom and sides of the bowl once more, and beat on low for an additional 30 seconds.

Rest the muffin batter.

Cover the bowl with plastic wrap and let the batter rest at room temperature for 1 hour.

Prep the oven and muffin pan.

While the batter is resting, position a rack in the center of the oven and preheat the oven to 400°F using the convect setting.

Prepare two muffin pans by spraying the inside and border of every other cavity in the muffin pan generously with cooking spray.

Assemble the muffins.

Use a 1-tablespoon or 3-tablespoon cookie dough scoop to fill each sprayed cavity with 6 tablespoons of the batter.

Make the cinnamon sugar topping.

Whisk together the granulated sugar and cinnamon for the cinnamon sugar topping in a small bowl.

Sprinkle the top of each cavity with 1 teaspoon of the cinnamon sugar each.

Bake the muffins.

Bake each muffin pan for 20 to 22 minutes, or until the muffins are domed and golden brown around the edges.

Cool and unmold the muffins.

Cool the muffins in the muffin pans on a wire rack for 15 minutes.

Use an offset spatula to run underneath the edges of the banana muffin tops to prevent them from sticking in the pan.

After unsticking the muffin tops, keep cooling the muffins in the pans completely to room temperature.

Serve and store.

Serve warm or at room temperature.