In a separate medium size mixing bowl combine eggs, flour, milk, salt, and dry powdered mustard and whisk until most of the clumps are gone (some may remain).
Bake uncovered for 40 minutes. Add remaining cheese to the top of the casserole and return to 350F degree oven for an additional 5 minutes or until firm.
If you've tried this recipe, we want to hear about it! Come back and leave us a comment or rating!
If you prefer to use cream of tarter to fluff up the eggs instead of flour, use 1 teaspoon.
Flour can be omitted, if you are looking for gluten-free.