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 until mostly smooth with a few small lumps. You should have about 1 1/4 to 1 1/2 cups.

Whisk the wet ingredients: Add sugar, eggs, oil, yogurt (or sour cream), and vanilla to the bananas. Whisk until well combined and glossy.

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

Combine gently: Add the dry mixture to the wet mixture. Stir with a spatula until just combined. A few streaks of flour are okay; don’t overmix.

Prepare the blueberries: Toss the blueberries with 1 tablespoon of flour. This helps prevent them from sinking.

Fold in add-ins: Gently fold the blueberries into the batter. If using nuts or chocolate chips, fold them in now as well.

Fill the pan: Scrape the batter into the prepared loaf pan and smooth the top. For a prettier top, sprinkle a few extra blueberries or a light pinch of sugar.

Bake: Bake for 55–70 minutes, until the top is golden and a toothpick inserted in the center comes out with a few moist crumbs but no wet batter. Start checking at 55 minutes.

Cool properly: Let the loaf cool in the pan for 15 minutes. Then lift it out using the parchment and cool completely on a wire rack before slicing.