Combine first 5 ingredients in a large bowl; beat with a mixer at medium speed until smooth. Add egg; beat well.
Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, oats, baking soda, and salt in a medium bowl, stirring with a whisk. Add flour mixture to banana mixture in bowl; beat with a mixer at medium speed until well blended. Stir in chocolate chips.
Drop batter by heaping tablespoonfuls 2 inches apart onto baking sheets coated with cooking spray. Bake at 350° for 18 minutes or until golden. Cool on pans 2 minutes. Remove cookies from pans; cool completely on wire racks.