For the sweet potato base, cook and mash the sweet potato, add melted butter and press into base of 9 x 13 dish. Alternatively, grate raw sweet potato, mix with melted butter and press into 9 x13 dish - this may take a bit longer to cook but is nicer. Beat eggs well. Mix together with flour to spinach or kale. Pour over the sweet potato base. Choose flavor of casserole and add these ingredients, making sure they get covered by the egg mixture. (You can add other ingredients like mushroom, broccoli, etc.) Bake at 350F for 50-60 minutes, or until egg is set.