Season the chicken with some salt and pepper and drizzle over with 1 tablespoon of oil. Mix well to coat, then place it in a 2 qt casserole dish; arrange in a single layer to ensure even cooking.
Bake into the preheated oven for 10 minutes.
While the chicken is cooking prepare sauce. In a skillet, heat the remaining tablespoon of oil. Add onion and sauté until translucent.
Add flour and whisk quickly for about a minute or so.
Carefully pour in the milk and continue whisking; as the mixture starts to bubble add garlic powder, onion powder, mustard powder, paprika, salt, and pepper.
Stirring thoroughly, let the mixture simmer on low, until thick and bubbly. Remove from the heat and add 1-1/2 cup of cheddar cheese, whisk well until cheese is melted.
Remove the casserole dish from the oven. Add a layer of cooked rice and then broccoli florets. Pour the prepared cheese sauce on top and gently toss to coat.
Sprinkle remaining 1/2 cup of cheese on top and bake for 20 minutes more, until broccoli is tender, and cheese on top is golden and bubbly.
Remove from the oven, garnish with fresh parsley, and serve warm.
Brown rice: Have this cooked before you start making the casserole.
Broccoli: Trim the leaves from the broccoli and cut the florets close to the stalk. Then trim the florets so they are roughly the same size. Alternatively, you can buy florets pre-cut.
Onion: We prefer sweet or yellow onion in this recipe.
Gluten-free flour: You can use regular flour if you do not have gluten restrictions.
Milk: Use non-dairy milk to make this recipe vegan.
Cheddar cheese: You can omit the cheese or use light/fat-free, or substitute with mozzarella, Colby, or parmesan.
Storage: Store wrapped in tinfoil or in an air-tight container in the fridge for up to 3-4 days.
Freezing: Freeze after cooking the chicken and adding the broccoli, rice, and sauce. Wrap tightly in tinfoil or store in an air-tight container. Freeze for up to 3 months, then thaw overnight in the fridge. Bake as directed. Alternatively, freeze after it has been cooked. Wrap tightly or store in an air-tight container, freeze for up to 3 months, then reheat in the microwave or oven.