Preheat oven to 350°.
Combine first 5 ingredients in a food processor; process until smooth.
Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and next 5 ingredients (through salt) in a large bowl. Add banana mixture to flour mixture, stirring just until moist. Stir in chocolate chips and walnuts until well combined. Divide mixture evenly between 2 (9 x 5-inch) loaf pans coated with cooking spray.
Bake at 350° for 50 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on a wire rack 10 minutes. Remove from pan; cool completely.