Preheat the oven to 350 degrees F. Spray a medium sized rectangle baking dish (about 11x7) with cooking spray and set aside.
Bring a large pot of water to boil. Add broccoli and boil for 3-4 minutes. Drain and set aside.
In a medium saucepan, melt butter over medium heat. Whisk in flour, garlic powder and paprika and cook for several minutes until golden. Add half & half and bring to a simmer until thickened. Remove from heat and stir in cheese (reserve 1/4 cup for topping). Stir in salt and black pepper. Taste and add salt as desired.
Arrange broccoli in the baking dish. Pour cheese sauce over the broccoli and gently stir to coat.
In a small bowl, combine crushed crackers with melted butter and stir in the remaining cheese. Sprinkle cracker mixture evenly over the casserole.
Bake uncovered at 350 degrees for about 20-25 minutes, or until sauce is bubbly and topping is browned. If topping isn't browned enough, place under the broiler for a few minutes.
Let stand 10 minutes before serving.
To freeze, bake and cool casserole completely, then cover tightly with plastic wrap and foil. Thaw in the refrigerator, then bake as directed in step 6.