Chocolate Bottom Banana Square

Its Sunday and as usual,Sunday is my extra cooking and baking day. Had been eying on making something using banana for days! So after some searching arounds on what to bake,I decided to do this. But only 10 minutes after its baked almost half has finished. Not sure if I can save it from my guests this evening. Huhuhu.
Lets check out the ingredients.

Ingredients: 
1/2 cup butter
1 cup sugar
1 egg
1 teaspoon vanilla
1 1/2 cups mashed banana (about 3 medium bananas)
1 1/2 cups flour
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1/4 cup baking cocoa
1 cup chocolate chips

Instructions: 
1. In mixing bowl, cream butter and sugar. Add egg, vanilla, and bananas, beating thoroughly.
2. In a separate bowl, combine flour, soda, baking powder, and salt. Add to creamed mixture and mix well.
3. Divide batter in half. Add the cocoa to one portion of the batter. Spread that portion in the bottom of a greased 9 x 13-inch baking dish. Spoon remaining batter on top, swirling gently with butter knife if desired, and sprinkle with chocolate chips. 4. Bake at 175 degrees for 25-30 minutes or until batter tests done with a toothpick or fork. Cool and cut into 24 squares.