Chocolate-Bottom Banana Squares

I am submitting this post to Aspiring Bakers #5 : Fruity March (March 2011), hosted by Jess@Bakericious. 

这个蛋糕很好吃，我觉得真的像Hearty Bakes说的

“you won't stop at one! ”。

食谱参考：Hearty Bakes

Ingredients:

1/2 cup Butter -113g (softened)
1 cup sugar ( i used 3/4 cup)
1 egg (lightly beaten)
1 teaspoon vanilla
3 medium ripe bananas (mashed)
1 1/2 cups flour
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1/4 cup cocoa powder ( i used Valrhona. Do use quality cocoa. It makes the whole world difference)
1 cup chocolate chips ( i used 1/2 cup)

Instructions:

1. In mixing bowl, cream butter and sugar till light and fluffy.
2. Drizzle in the eggs, vanilla and mashed bananas, beating thoroughly.
3. Sieve in the flour, baking soda, baking powder and salt to the creamed mixture in above step and mix it well.
4. Divide the batter into half. Add the cocoa powder to one portion of the batter. Spread that portion in the bottom of a greased 9inch square baking tin.
5. Spread the remaining plain batter on top the cocoa batter, swirl gently with a knife and sprinkle top with chocolate chips.
4. Bake at 180 degrees C for about 30 minutes or test batter done with a toothpick or fork. Cool and cut into squares to serve.