One Pan Scalloped Potatoes

6 medium potatoes, sliced thin
1/4 cup chopped onion
3 TBLS flour
1 tsp salt
1/4 tsp pepper
1/4 cup melted margarine
Shredded cheese of choice
2 1/2 cups milk

Put layers of potatoes in greased 9x13 pan. Sprinkle on layer:
1 TBLS onion
1 TBLS flour
1 TBLS margarine
salt/pepper
Handful of shredded cheese

Add another layer of potatoes and sprinkle with above. Add third layer of potatoes and sprinkle with above.

Pour milk on top.

Bake at 350 degrees, covered for 30 minutes. Uncover and bake 60 minutes. Let stand 10 mins when out of oven.