Step 1

Preheat oven to 400 degrees. Spray an 8X8 casserole with cooking spray.

Step 2

Layer 1/2 of potatoes into prepared dish. Top with onions.

Step 3

Top with remaining potatoes and salt and pepper to taste.

Step 4

In a medium saucepan, melt butter over medium heat and stir in flour.

Step 5

Add salt and stir constantly with whisk for one minute.

Step 6

Slowly stir in milk.

Step 7

Cook, stirring constantly, for approximately 5 minutes or until milk is hot and slightly thickened.

Step 8

Remove from heat and add shredded cheese. Stir until cheese is melted.

Step 9

Pour over the potatoes and cover with foil.

Step 10

Bake for 1 and 1/2 hours in oven.