Prep the pan and oven: Preheat to 350°F (175°C).
Grease a 9x5-inch loaf pan and line with a parchment sling for easy removal.
Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth with a few small lumps for texture.
Add wet ingredients: Whisk in the granulated sugar, brown sugar, oil (or melted butter), eggs, yogurt (or sour cream), and vanilla until well combined.
Mix dry ingredients: In a separate bowl, whisk together flour, baking soda, baking powder, salt, and cinnamon.
Combine gently: Add the dry ingredients to the banana mixture. Stir with a spatula until just combined. A few small streaks of flour are okay.
Fold in add-ins: If using nuts or chocolate chips, fold them in gently.
Don’t overmix—this keeps the bread tender.
Fill the pan: Scrape the batter into the prepared pan, smoothing the top. For a pretty finish, sprinkle a little turbinado sugar or place a sliced banana on top.
Bake: Bake for 55–65 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top browns too fast, tent with foil for the last 10–15 minutes.
Cool properly: Let the loaf cool in the pan for 10–15 minutes, then lift it out and finish cooling on a wire rack.
Slice only when mostly cool for neat slices.