Heat the oven to 400°F and coat a 9-by-13-inch baking dish with cooking spray.
Combine the chicken, frozen cauliflower, hot sauce, cream cheese, garlic powder and salt directly in the dish.
Cover tightly with foil and bake for 30 minutes.
Uncover, stir until the cream cheese blends into the sauce and verify that center chicken pieces reach 165°F.
Top with Monterey Jack and bake uncovered for 10 to 15 minutes, until browned at the edges and the cauliflower is fork-tender.
Rest for 5 minutes so the sauce thickens around the florets.