Baked Macaroni and Cheese

Ingredients

• 1/2 pound elbow macaroni
• 3 tablespoons butter
• 3 tablespoons flour
• 1 tablespoon powdered mustard
• 3 cups milk
• 1/2 cup yellow onion, finely diced
• 1 bay leaf
• 1/2 teaspoon paprika
• 1 large egg
• 12 ounces sharp cheddar, shredded
• 1 teaspoon kosher salt
• Fresh black pepper