Alton Brown's Baked Macaroni and Cheese

Ingredients

• 1 bay leaf
• some black fresh pepper
• 0.25 cup butter
• 1 egg
• 0.5 pound elbow macaroni
• 1 Tbsp flour
• 3 cups milk
• 1 Tbsp powdered mustard
• 0.5 cup panko bread crumbs
• 12 ounces paprika
• 0.5 cup shredded sharp cheddar
• 1 yellow diced onion