Preheat oven to 350 degrees F. Spray a bundt cake pan with non-stick spray. (I like to use the non-stick spray made specifically for baked goods- it really makes a difference! It's so fast! There's nothing worse than a cake that won't come out of a bundt pan...)
In large mixing bowl whisk together the butter and sugar. Add eggs, banana, vanilla and milk. Next, add in dry ingredients except chocolate chips, whisking until well combined. Stir in chocolate chips.
Bake 50 to 60 minutes at 350 degrees. Cool 10 minutes. Remove from pan. Fully cool prior to frosting.
Vanilla Buttercream Frosting: Whisk 1/2 cup butter with an electric mixer for 1 minute. Add 3 cups of powdered sugar, 1 cup at a time. Add in 1 tsp vanilla and 2 TBSP milk. Mix until smooth. Spread on cooled cake. Top with mini chocolate chips.