Preheat Your Oven: Preheat your oven to 350°F (175°C). Grease a 9×5-inch baking dish or line it with parchment paper.

Brown the Butter: In a medium saucepan, melt 1/2 cup of unsalted butter over medium to low heat. Cook until it turns golden brown with a nutty aroma (5-7 minutes). Transfer to a bowl and let it cool for 10 minutes.

Mix the Wet Ingredients: Add 1 cup of brown sugar to the cooled butter and mix until well combined. Add the 3 mashed bananas and mix again. Then add 1 egg, 1/4 cup of whole milk, and 1 1/2 teaspoons of cake batter flavor extract. Mix until fully incorporated.

Prepare the Dry Ingredients: In a separate bowl, whisk together 2 cups of flour, 1 1/2 teaspoons of baking powder, and 1/4 teaspoon of salt.

Combine Wet and Dry Ingredients: Gradually fold the dry ingredients into the wet mixture until just combined. Be careful not to overmix.

Add Sprinkles: Gently fold in 1/2 cup of rainbow sprinkles.

Transfer to Baking Dish: Pour the batter into the prepared 9×5-inch baking dish. Smooth the top and add a few more sprinkles for decoration.

Bake: Bake in the preheated oven for 1 hour. To prevent over-browning, cover the bread with aluminum foil halfway through baking.

Cool: Let the banana bread sit on the counter for 1 hour before slicing to ensure it sets properly and doesn’t fall apart.