Step 1

Prepare: Preheat oven to 375 F. Cut any broccoli florets larger than 2 inches into smaller pieces, and add all broccoli to large microwave-safe bowl. Cover and microwave until tender, about 5 minutes. Let them drain and steam out on paper towels (Note 5).

Step 2

Make Beef-Tomato Mixture: If wet, pat ground beef dry with paper towels. Add beef to large pan over medium heat. Crumbling beef with stiff utensil, cook until browned, about 5 minutes. Keeping everything in pan, stir in tomato sauce, celery, salt, garlic powder, and cayenne. Simmer for at least 10 minutes to thicken sauce (Note 5), stirring occasionally. Turn off heat and let moisture steam out.

Step 3

Assemble Casserole: Directly in 8x8 inch baking dish (Note 6), add broccoli, beef-tomato mixture, and half of cheddar cheese, carefully stirring together until well-mixed. Evenly top with remaining cheddar cheese. Sprinkle parmesan cheese on top.

Step 4

Bake & Cool: Bake uncovered at 375 F until casserole begins bubbling up sides and starts to brown on top, about 20 minutes. Let rest for about 10 minutes before cutting into it. Serve (Note 7).