Preheat the oven to 350 degrees F. Grease and flour one 8x5-inch loaf pan.
In large bowl, use an electric mixer to combine the butter and sugar. Add the baking soda, sour cream, eggs, bananas and vanilla. Blend well. Stir in the flour and chocolate chips, just until combined.
Pour the batter into the prepared pan and bake 40 to 50 minutes, or until a toothpick inserted into the center comes out clean.
Notes
You may also use 3 mini loaf pans- test after 35 minutes of baking.