Preheat oven to 350°.
Combine first 4 ingredients in a large bowl; stir with a whisk. Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, baking powder, and salt. Add flour mixture to sugar mixture; stir just until moist. Spread batter in an 8-inch square baking pan coated with cooking spray. Sprinkle with toffee bits. Bake at 350° for 22 minutes or until a wooden pick inserted in center comes out almost clean. Cool in pan on a wire rack.
Note: Store, covered, for up to 3 days.