Preheat the oven to 350F. Grease a 9x5-inch metal loaf pan. Set aside.
In a large bowl, whisk mashed banana and melted butter together until well-combined.
⅓ cup salted butter , 1 ½ cups mashed banana
Whisk in sugars until incorporated.
⅓ cup light brown sugar , ⅓ cup granulated sugar
Add eggs and vanilla, and whisk until well-combined.
2 large eggs, 1 teaspoon vanilla extract
Stir in flour, baking soda, and salt until combined.
1 ½ cups all-purpose flour , 1 teaspoon baking soda, ¼ teaspoon salt
Add chocolate chips, and whisk until just incorporated.
¾ cup semisweet chocolate chips
Pour the batter into your prepared loaf pan, and sprinkle with additional chocolate chips, if desired.
Bake for 40-50 minutes, or until a wooden toothpick inserted into the center comes out clean. I check the bread around 30 minutes and tent with foil if it is browning too quickly.
Let cool in pan for a 5-10 minutes.
Remove bread to wire cooling rack, and let cool completely before slicing.
Notes
Bananas: It’s important to use overripe bananas. I like to use bananas that are equal parts brown spots and yellow.
Butter: This recipe uses melted butter. The butter shouldn’t be hot and sizzling. I melt it about 80% of the way and then whisk it to let it finish melted.
Also, I use salted butter. If you're using unsalted butter, add an additional 1/4 teaspoon of salt.
Flour: It’s important to properly measure flour to avoid heavy or doughy banana bread. The proper way to measure flour is to stir it to break it up. Then lightly spoon it into a measuring cup and level it off.
Chocolate chips: I recommend going light on the chocolate chips on top. If the chocolate chips are too heavy, they can prevent the bread from rising properly.
Glass pan: If you're using a glass loaf pan, decrease the oven temperature by 25F. Also, begin checking the bread about 5-10 minutes sooner for doneness.
Baking time: Oven temperatures vary, so you may find that you need to adjust the time according to how your oven bakes.