Preheat the oven to 356°F (180°C). Prepare an 8-inch square baking pan by greasing and lining it with parchment paper. Mash the ripe bananas with a fork and set aside. In a mixing bowl, combine butter, palm sugar, sugar, and salt. Beat on medium speed until the mixture turns pale and fluffy.
Add the eggs one at a time, mixing well after each addition. Stir in the sour cream and mashed bananas. In a separate bowl, sift together all the dry ingredients. Gently fold the dry mixture into the batter until just combined.
Pour the batter into the prepared pan. If decorating with banana slices, bake for 20 minutes first, then arrange the slices on top. For a plain loaf, continue baking without interruption. Bake for a total of 60–75 minutes, or until a skewer inserted in the center comes out clean. Remove from the oven and let cool completely on a wire rack before slicing. Enjoy your homemade copycat Starbucks banana bread!
Notes
Swap smartly – Plain yogurt works beautifully as a substitute for sour cream. Both keep the banana bread moist and tender.
Nutty upgrade – Fold in walnut slices for crunch, or sprinkle them on top before baking for that classic Starbucks-style finish.
Decorate halfway – After 20 minutes of baking, the surface begins to set. That’s the perfect time to press banana slices or walnut pieces gently on top so they won’t sink into the batter.
Don’t overmix – When adding the dry ingredients, mix just until combined. Overmixing can make the bread dense instead of fluffy.
Check for doneness – Baking time can vary depending on your oven. Always test with a skewer; if it comes out clean or with just a few crumbs, your bread is ready.
Cool completely before slicing – Letting the loaf rest on a wire rack helps lock in moisture and makes cleaner slices.