1Preheat oven to 350 deg F.
Spray casserole dish with cooking oil spray or grease casserole dish with shortening.
2Saute onion in butter.
3Add 1/4 cup flour, salt, mustard and pepper to onion and butter.
4Gradually add milk/cream whisking to make a nice white sauce. Stir and cook until thick.
5Add shredded cheese, potatoes and ham (if so desired). Stir all ingredients together. Add a bit more milk if needed. The potatoes will absorb some of the milk so you may need a little more. Pour into greased casserole dish.
Bake uncovered in 350 deg oven for about 30 min
Then, spread more cheese on top and bake for 10-15 min longer before removing from oven.
ENJOY! These are very cheesy and rich, yummy!