1Heat oven to 375°F. In 10-inch skillet, heat oil over medium-high heat. Add mushrooms and onion; cook 5 to 7 minutes, stirring frequently, until tender. Meanwhile, microwave broccoli with cheese sauce as directed on box.
2Add broccoli, ricotta and chicken to skillet; stir to combine. Spray 8-inch (2-quart) casserole with nonstick cooking spray. Add chicken mixture to casserole.
3Unroll dough; separate into 2 rectangles. Place rectangles over top of casserole, tucking corners into dish as needed (trim excess dough, if desired).
4Bake 20 to 25 minutes or until golden brown and edges are bubbly.