Prep the pan and oven: Heat the oven 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 bananas until mostly smooth with a few small lumps for texture.
Whisk in wet ingredients: Add Greek yogurt, oil, eggs, vanilla, brown sugar, and granulated sugar.
Whisk until smooth and glossy.
Combine dry ingredients: In a separate bowl, whisk flour, baking soda, baking powder, and salt to evenly distribute the leaveners.
Fold together: Add dry ingredients to wet. Stir gently with a spatula until just combined. Stop when you no longer see dry streaks.
Fold in any add-ins.
Pan and smooth: Scrape batter into the pan and smooth the top. For a bakery-style split, run a thin line of oil down the center with a knife.
Bake: Bake 50–60 minutes, until the top is golden and a toothpick comes out with a few moist crumbs. If browning too fast, tent loosely with foil at the 45-minute mark.
Cool properly: Cool in the pan 10–15 minutes, then lift out to a rack.
Let it set at least 30 minutes before slicing for clean pieces.