Prep the pan and oven: Preheat your 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 with a fork until mostly smooth. A few small lumps are fine.
Whisk in wet ingredients: Add granulated sugar, brown sugar, oil (or melted butter), eggs, vanilla, and yogurt or sour cream if using. Whisk until well combined and slightly glossy.
Add dry ingredients: Sprinkle the flour, baking soda, salt, and cinnamon over the wet mixture.
Use a spatula to gently fold until just combined. Do not overmix—a few streaks of flour are okay.
Stir in add-ins: If using chocolate chips, nuts, or other mix-ins, fold them in now.
Fill the pan: Pour the batter into the prepared loaf pan and smooth the top. For a pretty finish, sprinkle a little sugar on top or add a few chocolate chips.
Bake: Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top is browning too fast, tent with foil for the last 10–15 minutes.
Cool: Let the bread cool in the pan for 10–15 minutes, then lift it out and cool on a rack.
Slice when it’s just warm or fully cooled for neater slices.