Line a 12 tin muffin liner with 12 liners or 2 liners with 6 muffin tins in each (Your preference) and set aside. Melt the butter and prepare to measure the rest of your ingredients as it cools.
Using a fork, mash the bananas. Add into a large bowl.
1 1/4 cups bananas
Add in white sugar, eggs, condensed milk, oil and vanilla. Whisk until well combined (1-2 minutes).
3/4 cups white sugar, 2/3 cup sweetened condensed milk, 2 eggs room temperature, 1 tbsp vanilla, 1/4 cup vegetable oil
Add in flour, baking soda, baking powder, cornstarch, and salt. Using a spatula, gently fold until a batter forms. Do not over-mix!
2 cups all-purpose flour, 3/4 tsp baking soda, 3/4 tsp baking powder, 1 tsp cornstarch, 1/2 tsp salt
Toss in the mini chocolate chips and mix in a few times. Do not over-mix!
3/4 cups mini chocolate chips
Evenly divide the batter between 12 liners, they should be almost or all the way full. Using a cookie scooper helps big time to minimize the mess. Sprinkle extra chocolate chips and white sugar on top for a crisp top.
Bake the muffins at 425°F for 5 minutes, then turn down to 375°F and bake for an additional 20-25 minutes. If you are baking in regular liners, the muffins should bake at 425°F for 5 minutes, then 375°F for 12-15 minutes. Since tulip liners have a taller bake they require more time. The muffins are ready when a toothpick inserted comes out clean.
These muffins stay fresh covered at room temperature for a few days, or in the refrigerator in an airtight container for up to 1 week!