Set your oven to 350°F (175°C). Position a rack in the lower third of the oven. This prevents the top from browning too quickly.

Grease a 9x5 inch loaf pan with butter or non-stick spray. For easy removal, line the bottom and long sides with a strip of parchment paper, leaving overhang on both sides like handles.

If you haven't already, set out your butter, eggs, and sour cream. Room temperature ingredients blend together much more smoothly.

In a medium bowl, whisk together the flour, baking soda, salt, and cinnamon until evenly combined.

Keep this bowl ready to add to the wet mixture later.

Peel the bananas into a bowl. Using a fork or potato masher, mash until mostly smooth with some small chunks remaining.

You should have about 1½ cups of mashed banana. A little more or less is fine.

In a large bowl using a hand mixer (or stand mixer with paddle attachment), beat the softened butter and brown sugar together on medium-high speed until light and fluffy, about 3 minutes. The mixture should be noticeably lighter in color and texture.

Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed.

Beat in the sour cream and vanilla extract until combined.

Mix in the mashed bananas on low speed until just combined. The mixture may look slightly curdled at this point. That's normal.

Add the flour mixture to the banana mixture all at once.

Using a rubber spatula, fold the dry ingredients into the wet using broad, gentle strokes. Scrape the bottom and sides of the bowl.

Mix only until you no longer see streaks of dry flour. Some small lumps are fine. Do NOT overmix.

If using walnuts, pecans, or chocolate chips, fold them in with 2-3 more gentle strokes.

Pour the batter into the prepared loaf pan. Use a spatula to spread it evenly and smooth the top.

For extra crunch, sprinkle a few tablespoons of raw sugar or additional chopped nuts on top before baking.

Confirm your oven is preheated to 350°F (175°C) with the rack positioned in the lower third.

Place the pan in the oven and bake for 55-65 minutes. Do NOT open the oven door for the first 45 minutes—this is critical.

After 55 minutes, the bread is done when the top is deeply golden brown, the edges pull slightly away from the pan, and a toothpick inserted into the center comes out clean or with just a few moist crumbs.

If the top is browning too quickly before the center is done, tent loosely with aluminum foil for the last 15-20 minutes.

Let the bread cool in the pan on a wire rack for 15 minutes. This allows the structure to set.

Using the parchment paper handles (or by running a knife around the edges), carefully lift or turn the bread out onto the wire rack.

Let the bread cool completely on the rack, about 30-45 minutes more, before slicing.

Use a serrated knife for clean slices. Serve plain, toasted with butter, or slightly warm.

Pour batter into greased 9x5 loaf pan. Smooth top with spatula.

Bake 55-65 minutes at 350°F.

Pour batter into smaller 8x4 loaf pan. Batter will mound higher in the pan.

Increase baking time to 60-70 minutes. Check center carefully, smaller pans can trap moisture.

Divide batter among 3-4 mini loaf pans (5x3 inch). Fill each about ⅔ full.

Reduce baking time to 35-45 minutes. Great for gifting!

Line standard muffin tin with paper liners. Fill cups about ¾ full.

Bake 20-25 minutes at 350°F. Makes about 12 muffins.

Preheat oven to 350°F.

Position rack in lower third of oven.

Bake 55-65 minutes. Tent with foil if browning too fast.

Test with toothpick for doneness.

Reduce temperature to 325°F (convection runs hotter).

Bake 50-55 minutes. Check 5-10 minutes earlier than standard time.

May brown more evenly but watch carefully.