Cook the macaroni according to package instructions. Drain and rinse with cold water to stop the cooking. Drain again and set aside.
In a saucepan, melt the butter over medium heat. Sprinkle the flour into the butter and stir it with a whisk. Cook for 2 minutes. Whisk the warmed milk into the flour mixture, working out any lumps. Cook until the sauce thickens, about 2 minutes. Remove from the heat, add the cheeses, and stir until melted and smooth; season with salt and pepper. Fold the cheese sauce into macaroni. Pour the mac and cheese into a shallow pan and refrigerate until cold, at least 2 hours.
Shape the cold mac and cheese into meatball-sized balls and place them onto a waxed paper-lined tray. Freeze the balls overnight.
Beat the eggs and 2 tablespoons milk together to form an egg wash and pour it into a shallow bowl. Put the bread crumbs into another shallow bowl. Remove the mac and cheese balls from the freezer. Dip the frozen balls into the egg wash then into the bread crumbs. Put the balls back into the freezer until you are ready to fry.
Heat the oil in a deep-fat fryer to 350 degrees F. Fry the mac and cheese balls until they are golden brown and center is hot, about 5 minutes. Serve hot with your favorite marinara or Alfredo sauce or combination or both for dipping.