Cook brown rice according to package and set aside.
In a medium saucepan, bring the stock to a boil.
Reduce the heat to low and add the broccoli.
Simmer for 10 minutes.
Drain and set aside.
In a pan heat 1 tablespoon oil.
Add the onion and mushrooms and cook for 5 minutes.
Set aside.
Preheat oven to 350 F.
In a seperate pan over medium heat add the remaining oil.
Stir in flour and whisk for 5 minutes.
Add the milk and stir.
Stir in 2 cups of the cheese, allow it to melt.
Transfer the mushroom mixture into a baking dish.
Add sour cream, broccoli, cheese sauce, and rice.
Add salt and pepper to taste.
Mix.
Bake for 30 minutes.
Top with the remaining cheese and bake for 10 minutes longer.
Serve.