Never-Fail Scalloped Potatoes | Reader's Digest Canada

Ingredients

• 2 tbsp butter
• 3 tbsp all-purpose flour
• 1 tsp salt
• 1/4 tsp pepper
• 1-1/2 cups fat-free milk
• 1/2 cup shredded reduced-fat cheddar cheese
• 2 lb red potatoes (peeled and thinly sliced (about 4 cups))
• 1 cup thinly sliced onions (divided)