Heat oven to 350 F. Grease a 12x8-inch (2-quart) baking dish.
Cook broccoli as directed on package; drain.
Arrange broccoli in prepared baking dish, and layer chicken over broccoli.
In small bowl, combine soup, mayonnaise, and True Lemon; mix well.
Spread the mixture over the chicken, and sprinkle with cheddar cheese.
In small bowl, combine crumbs and margarine then sprinkle over top.
Bake at 350 F for 30-35 minutes or until thoroughly heated. Serve hot.