Preheat oven to 350 degrees. Grease a 2 quart casserole dish.
Melt butter over medium-low heat. Whisk in flour and cook for 1-2 minutes, to remove the raw flour taste.
Slowly whisk in stock and milk. Season with salt, pepper, onion powder, and garlic powder. Continue cooking over medium heat until thick and bubbly, whisking constantly.
Remove from heat and add in cooked rice, cooked broccoli, and 1 cup cheddar cheese.
Pour in a casserole dish and top with remaining cheddar cheese and Parmesan. Bake for 30-35 minutes, or until lightly browned.
To cook broccoli, place raw or frozen broccoli florets in boiling water and cook for 2 minutes until JUST crisp tender. You can alternatively steam the broccoli for 2-3 minutes.
Chicken stock or vegetable stock can be used to make the creamy sauce.
Gluten Free Broccoli Rice Casserole: Use 1:1 gluten free flour blend in place of all purpose flour to keep this casserole gluten free.
Storing Broccoli Cheese Rice Casserole: Leftover casserole can be stored in the refrigerator for 3-4 days.
Preparing the Broccoli Cheese Rice Casserole in Advance: This casserole can also be prepared in advance. Simply prepare up to baking and cover tightly with foil. Refrigerate for up to 24 hours before baking or freeze for up to 3 months. To cook this casserole from frozen, bake at 350 degrees for 60 minutes covered, and then uncover and bake for an additional 15 minutes.