Adjust the oven rack to the lower third position and preheat the oven to 350°F (177°C). Lowering the oven rack prevents the top of your bread from browning too much, too soon. Grease a 9×5-inch loaf pan with nonstick spray. Set aside.

In a medium bowl, whisk the flour, baking soda, salt, and cinnamon together. Set aside.

In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the butter and brown sugar together on medium-high speed until light and creamy, about 3 minutes. (Here’s a helpful tutorial if you need guidance on how to cream butter and sugar.) With the mixer running on medium speed, add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed. Beat in the mashed bananas, yogurt/sour cream, and vanilla until combined.

Add the dry ingredients into the wet ingredients and beat on low speed just until combined. Do not over-mix. Fold in the nuts/chocolate chips, if using. The batter should be thick.

Pour and spread the batter into the prepared baking pan. Bake for 60–65 minutes, making sure to loosely cover the pan with aluminum foil halfway through, to prevent the top from getting too brown. The bread is done when a toothpick inserted in the center comes out clean with only a few small moist crumbs. Cool the bread in the pan set on a cooling rack for 1 hour. Remove the bread from the pan and place it directly on the rack to cool completely before slicing and serving.

Store wrapped tightly at room temperature for up to 3 days or in the refrigerator for up to 1 week.