Preheat and prep the pan: Set your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with a parchment sling for easy removal.

Make the quick caramel: In a small saucepan, melt 6 tablespoons unsalted butter over medium heat. Stir in 1/2 cup packed brown sugar and cook, whisking, until smooth and bubbling, about 2 minutes. Remove from heat and slowly whisk in 1/3 cup heavy cream and 1 teaspoon vanilla. Set aside to cool slightly; it will thicken as it sits.

Mix dry ingredients: In a medium bowl, whisk together 2 cups flour, 1 teaspoon baking soda, 1/2 teaspoon salt, and 1 teaspoon cinnamon.

Mash the bananas: In a large bowl, mash 3 very ripe bananas until mostly smooth. Aim for about 1 1/2 cups. A few small lumps are fine.

Whisk wet ingredients: To the bananas, add 2 eggs, 1/3 cup neutral oil, 1/3 cup sour cream, 1 teaspoon vanilla, 1/2 cup brown sugar, and 1/4 cup granulated sugar. Whisk until combined.

Combine batter: Add the dry ingredients to the wet and fold gently with a spatula until just combined. Do not overmix. If using nuts or chocolate chips, fold them in now.

Layer with caramel: Pour half the batter into the prepared pan. Drizzle about half of the caramel sauce over it, then gently swirl with a butter knife. Add the remaining batter and repeat with more caramel, reserving 2–3 tablespoons for topping after baking.

Bake: Smooth the top and bake for 55–65 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Tent loosely with foil after 40 minutes if the top is browning too quickly.

Cool and finish: Let the loaf cool in the pan for 15 minutes, then lift it out to a wire rack. Warm the reserved caramel slightly if needed and drizzle over the top. Cool at least 30 minutes before slicing for clean pieces.

Serve: Slice thick and enjoy warm or at room temperature. A pat of butter or a scoop of vanilla ice cream takes it fully into dessert territory.