This recipe is from my sisters in law Dee and Deborah. You can adjust the amounts for larger crowds
For two people:
4 peeled small potatoes, sliced
boil potatoes in salted water until fork tender
Sauté one finely chopped onion
Make a roux of 1/8 cup of flour
2 tbsp butter
Cook roux for a few minutes
Add 1 cup milk
Mix until thick
Add sautéed onions, salt, pepper, garlic powder and a few tbsp of Parmesan cheese
Drain potatoes and mix all together.
For a large crowd you can use 1 cup of flour, 2 sticks butter and half gallon of milk. Adjust Parmesan cheese to taste.