Preheat your oven to 180 C. Get out a 2 quart baking dish and lightly grease with butter.

In a large non stick pan, melt the butter and cook onion on medium low heat until softened and translucent, then whisk in the in the flour, garlic powder, and pepper. Cook an additional 2 minutes. While whisking, gradually pour in the cold milk. Continue whisking over medium heat until thick and bubbly then remove from the heat and add stir in the mustard powder, paprika, cream cheese and 1½ cups cheddar cheese. Stir until melted, taste and adjust with salt if desired.

Cook broccoli in a pot of boiling water for about 2-3 minutes, does not need to be cooked through 100% as it will cook more in the oven. Drain broccoli, then stir together the rice, broccoli, and cheese sauce and pour into the prepared casserole dish, top with the rest of the cheese and bake for 30-35 or until bubbly and the cheese is starting to brown. Remove from oven and let rest 5 minutes, serve.