Yummy Low-Fat Mac & Cheese

Ingredients

• 1 tablespoon unsalted butter
• 3 tablespoons unbleached all-purpose flour
• 1 teaspoon dry mustard
• 1/2 teaspoon paprika
• 1/2 teaspoon kosher salt
• 1 1/2 cups nonfat milk
• 1 cup nonfat sour cream
• 1 egg, lightly beaten
• 2 cups shredded reduced-fat cheddar cheese
• 4 cups cooked elbow macaroni (from about 2 cups dried)
• 1/4 cup corn flake crumbs or 1/4 cup dried breadcrumbs