Preheat oven to 350.
Cream butter. Add bananas, sugars, vanilla, and eggs and mix well. Add flour, soda, and salt and mix well. Mix in 1/2 cup of chocolate chips.
Spread into greased 13x9 inch baking pan. Sprinkle the remaining 1/2 cup of chocolate chips on top.
Bake at 350 for 5 minutes. Use a knife to swirl the melted chips on top. Return to oven and bake another 25-30 minutes. Cool and cut into squares.
Note: These freeze well.