Heat oven to 350F degrees. Lightly mist a casserole dish with nonstick spray. I usually use a pretty oval dish, but you could use an 8- or 9-inch square dish if you like.
In a large bowl, add cooked rice, spinach, butter, onion, salt and cheese. In a 4-cup measure, pour milk and add eggs. Whisk to combine. Pour into the bowl with rice-spinach mixture and stir well to combine.
Pour into prepared casserole dish and bake for 45 minutes.
Remove from oven and serve.
Serves 6.
