Sweet Potato Gratin on BakeSpace.com

Ingredients

• 5 tbsp unsalted butter
• 1 large onion, chopped
• 1/2 cup all-purpose flour
• 2 cups skim milk
• 1 tbsp fresh rosemary, chopped
• 1 tsp kosher salt
• Freshly ground black pepper
• 3 large sweet potatoes, peeled and shredded
• 2 cups cheddar cheese, shredded
• 1 slice whole-wheat bread, ground in a food processor