Preheat oven to 350°F and place in a 12-piece muffin tin with paper liners.
In a mixing bowl, combine mixture together 8 tablespoons softened butter with 2/3 cup sugar. Add 2 lightly beaten eggs.
Add 3 mashed bananas and 1 teaspoon of vanilla extract and mix until combined.
In a separate bowl, whisk together the dry ingredients: 1 1/2 cups flour, 1 teaspoon baking soda, and 1/2 teaspoon salt. Mix the dry ingredients with the wet ingredients until blended.
Add 3/4 cup of chocolate chips. Divide batter evenly into 12-piece muffin tin and sprinkle remaining 1/4 cup chocolate chips evenly over top. Bake at 350°F on center rack for 25-30 minutes or until surface is golden and a toothpick inserted in center comes out clean.