Spread about 2 tablespoons of beans on each tortilla. Combine soup and sour cream; stir in chicken. Spoon 1/3 to 1/2 cup down the center of each tortilla; top each with 1 tablespoon cheese. , Roll up and place seam side down in a greased 13x9-in. baking dish. Pour enchilada sauce over top; sprinkle with the onions, olives and remaining cheese. , Bake, uncovered, at 350° for about 35 minutes or until heated through. Just before serving, sprinkle lettuce around enchiladas if desired. Freeze option: Cover and freeze unbaked casserole. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Bake casserole as directed, increasing time as necessary to heat through and for a thermometer inserted in center to read 165°.