My Family's Favorite San Giorgio Macaroni and Cheese

Ingredients

• 1 lb elbow macaroni, uncooked
• Salt, for pasta water
• 4 tbsp unsalted butter
• 1/4 cup all-purpose flour
• 4 cups whole milk
• 2 cups sharp cheddar cheese, shredded
• 1 cup mozzarella cheese, shredded
• 1 tsp Dijon mustard (optional)
• 1/2 tsp paprika
• Salt and pepper, to taste
• 1/2 cup breadcrumbs (optional)
• 2 tbsp grated Parmesan cheese (optional)
• 2 tbsp unsalted butter, melted (optional)