Preheat oven to 350°F (177°C). Line a 9×5-inch loaf pan with parchment paper, leaving overhang on the long sides, or grease well.
In a medium bowl, whisk together the flour, baking soda, salt, and cinnamon. Set aside. 2 cups + 2 Tablespoons (255 g) all-purpose flour 1 teaspoon baking soda 1 teaspoon fine sea salt
In a large bowl, whisk together the brown sugar, granulated sugar, oil, and peanut butter until smooth and glossy with no visible streaks of peanut butter. ¾ cup (150 g) packed light brown sugar ½ cup (100 g) granulated sugar ¼ cup (60 mL) neutral oil (vegetable, canola, or avocado) ½ cup (128 g) creamy peanut butter
Whisk in the eggs one at a time, mixing well after each addition until the batter looks thick and emulsified. 2 large eggs
Stir in the mashed bananas, sour cream (or Greek yogurt), and vanilla extract until fully combined. ½ cup (113 g) sour cream or Greek yogurt 1 ½ cups (340 g) very ripe bananas 2 teaspoons vanilla extract
Add the dry ingredients to the wet ingredients and gently fold with a spatula just until no dry flour remains. Do not overmix.
If adding chocolate chips, fold them in gently. (Tossing them with a teaspoon of flour helps prevent sinking.) Optional: ¾ cup chocolate chips
Pour batter into prepared pan and smooth the top. Bake for 60–70 minutes, tenting loosely with foil after about 45 minutes if the top is browning too quickly.
The bread is done when a toothpick inserted into the center comes out with a few moist crumbs and the internal temperature registers 205–210°F.