01 - Cook the elbow macaroni in boiling salted water according to package directions until al dente. Drain thoroughly and set aside.
02 - In a saucepan over medium heat, melt 2 tablespoons of butter. Stir in the flour and cook for 1 minute, whisking constantly to form a roux. Gradually whisk in the milk, stirring until the sauce is smooth and thickened, approximately 3 minutes.
03 - Add the 2 cups of shredded cheddar cheese, salt, black pepper, and optional paprika to the sauce. Stir continuously until the cheese is fully melted and the sauce is smooth.
04 - Gently fold the cooked macaroni into the cheese sauce, ensuring each piece is evenly coated. Remove from heat and allow to cool slightly.
05 - Lay out the 8 slices of bread.Spread 1 tablespoon of butter evenly on one side of each slice.
06 - On the unbuttered side of 4 bread slices, place 1 slice of cheddar or American cheese. Top with a generous portion of the prepared macaroni and cheese. Place another slice of cheese over the macaroni and cheese.
07 - Top each filled slice with a remaining bread slice, ensuring the buttered side faces outward.
08 - Heat a skillet or griddle over medium-low heat. Place the assembled sandwiches in the hot skillet. Cook for 3 to 4 minutes per side, pressing gently with a spatula, until the bread is golden brown and crisp, and the internal cheese is fully melted.
09 - Remove the grilled sandwiches from the skillet. Allow them to rest for 1 minute before slicing in half and serving hot.