Preheat oven to 350°F. In a rice cooker add quinoa and water. In steamer basket add frozen broccoli. Cook for 18-20 minutes, or until water is absorbed. Fluff with a fork and set aside. While quinoa is cooking, melt butter. Whisk in gluten free flour. Add onion and garlic, sauté for 5 minutes - stirring as needed. Next whisk in milk. Simmer for 5 minutes, until thickened. Stir in buffalo hot sauce. Remove from heat and stir in cheddar cheese, stirring until completely melted. In a large bowl, toss cooked quinoa and steamed broccoli together. Carefully pour sauce over quinoa/broccoli, stirring. Transfer to baking dish and top with grated cheddar cheese. Bake for 20-25 minutes, or until the top is slightly browned.