Grilled Mac & Cheese Sandwich
4 tablespoons unsalted butter, divided
4 cups warm prepared macaroni and cheese
2 thinly sliced onions
Kosher salt and pepper to taste
8 slices sourdough bread
12 slices sharp cheddar cheese
Make macaroni and cheese according to the recipe or box. Spread it into an 8-inch-square baking dish around 3/4 inch thick. Wrap the dish with plastic wrap and then place it into the refrigerator to chill until firm. This will take about 45 minutes. After the macaroni and cheese is firm, remove it from the refrigerator and cut it into squares that are smaller than the slices of bread being used and then set it aside.
Melt two tablespoons of butter in a skillet over medium heat. Sauté the onions, stirring them until they are caramelized. This wiill take about 20 minutes. If desired, season the onions with salt and pepper to taste.
Heat a panini grill to medium heat while preparing the sandwiches. Melt the remaining butter and brush a little on one side of each slice of bread. Place the butter side down on the panini grill, followed by a slice of cheese, one macaroni and cheese square and then another slice of cheese. Place the second piece of buttered bread to complete the sandwich, buttered side up.
Cook the sandwich until the cheese begins to melt and the bread turns a golden brown. This will take approximately 5 minutes. Then, build each additional sandwich until all four are complete.
As an alternative, you may also add barbecue pork, beef or chicken to the sandwich before grilling it.