Prep your pan and oven. Heat 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 ripe bananas until mostly smooth with a few small lumps for texture.

Whisk in wet ingredients. Add granulated sugar, brown sugar, melted butter, oil, eggs, sour cream, and vanilla. Whisk until the mixture looks glossy and well combined.

Combine dry ingredients. In a separate bowl, whisk flour, baking soda, baking powder, salt, and cinnamon until evenly mixed.

Bring it together. Add the dry ingredients to the wet. Using a spatula, fold gently until you no longer see dry flour. Do not overmix. If using nuts or chocolate chips, fold them in now.

Pan and top. Pour the batter into the prepared loaf pan. Smooth the top and sprinkle with a light layer of turbinado sugar if you like a bakery-style crust.

Bake. Bake for 55–70 minutes, depending on your oven. Start checking at 55 minutes. The bread is done when a toothpick inserted in the center comes out with a few moist crumbs but no wet batter.

Cool properly. Let the loaf cool in the pan for 15 minutes. Lift it out using the parchment and cool completely on a wire rack before slicing. This helps the crumb set and stay moist.