Leftover Ham -n- Potato Casserole

INGREDIENTS

• 6 small potatoes, peeled and cubed
• 3 tablespoons butter
• 2 cups cubed fully cooked ham
• 1 small onion, finely chopped
• 1/4 cup butter
• 3 tablespoons all-purpose flour
• 1 1/2 cups milk
• salt and ground black pepper to taste
• 1 (8 ounce) package shredded Cheddar cheese
• 1/4 cup bread crumbs