After trying several different recipes, I finally combined a couple, made some changes, and voila! 

Ingredients:

• 3 extra-large potatoes, peeled washed and sliced
• 1 and 1/2 cups milk
• 3 tablespoons flour
• garlic powder*
• black pepper*
• 1 cup shredded cheese
• 4 tablespoons low sodium margarine or no salt butter
• *I use a garlic-pepper blend that I found at Sam’s Club.

Preheat oven to 375 degrees.  Grease/spray your 2 quart casserole dish.

On stovetop, mix together margarine, milk, flour, and spices (seasoning to taste).  Heat on med-low heat until sauce starts to thicken, stirring constantly.  Once sauce thickens (not as thick as pudding, more like cake batter) remove from heat.

Layer half the sliced potatoes in your casserole dish.  Pour half the sauce on top.  Sprinkle half the cheese.  Layer the rest of the potatoes, sauce and cheese.  (if the sauce runs out, quickly mix together half a cup of milk and a tablespoon of margarine or butter together on med heat and pour that over the casserole.)

Cover and bake for 40 minutes.

Remove cover, and replace for another 20 minutes. (During this 20 minutes is when I make the meat and vegetables to go with the potatoes.)

Potatoes should be slightly brown on top and tender all the way to the bottom.

Tasty additions: 

chopped onions

fried and chopped bacon

ham/chicken pieces