Ham and Scalloped Potatoes

Ingredients (11)

• ✓ cooking spray
• + 8 potatoes, peeled and thinly sliced add to pantry
• + ½ cup butter add to pantry
• + 1 onion, finely chopped add to pantry
• + ½ cup all-purpose flour add to pantry
• + 2 teaspoons Dijon mustard add to pantry
• + 1 teaspoon salt add to pantry
• ✓ ¼ teaspoon ground black pepper
• ✓ 3 cups milk
• + 2 cups shredded Cheddar cheese add to pantry
• + 3 cups diced ham add to pantry