Prep your pan and oven: Heat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with a parchment sling for easy removal.

Mash the bananas: In a large bowl, mash the bananas until mostly smooth. A few small lumps are fine.

Whisk in the wet ingredients: Add the melted butter, sour cream, granulated sugar, brown sugar, eggs, and vanilla. Whisk until smooth and glossy.

Combine the dry ingredients: In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.

Bring it together: Sprinkle the dry mixture over the wet mixture and fold gently with a spatula until just combined. Stop when you no longer see streaks of flour.

Add mix-ins (optional): Fold in nuts or chocolate chips. Don’t overmix.

Pan and top: Pour the batter into the loaf pan. Smooth the top. For a pretty finish, sprinkle with coarse sugar or lay a halved banana, cut side up, on top.

Bake: Bake for 55 to 70 minutes, depending on your oven and pan. The loaf is done when a toothpick inserted in the center comes out mostly clean with a few moist crumbs.

Cool correctly: Let the bread cool in the pan for 15 minutes, then lift it out and cool on a wire rack for at least 1 hour before slicing.

Slice and enjoy: Use a serrated knife for neat, soft slices.