Preheat oven to 325 degrees.
In a large skillet heat bacon grease over medium heat. Cook onions, garlic, salt, pepper and basil for five minutes. Add chicken broth and broccoli and cook for five minutes more, or just until the broccoli starts to become tender. Remove from heat and mix remaining ingredients together, except the rice. Place half of the mixture into a buttered two-quart baking dish, spread the cooked rice over this layer. Top with remaining broccoli mixture. Bake 40 minutes uncovered. Remove from oven and allow casserole to set 15 minutes before serving.
http://robertstjohn.com/recipes/mushroom-bechamel-sauce/Yield: six to eight servings