Place sauerkraut in a colander and rinse with cold water. Drain well, using a spoon to press out excess liquid. Set aside.
. Lightly coat one side of each bread slice with cooking spray. Place four bread slices, coated sides down, on a work surface. Top with chicken, sauerkraut, apple slices/ grated apple, and cheese.
Top with the remaining four bread slices, coated sides up. Coat an unheated grill pan or large skillet with cooking spray. Preheat over medium-low heat for 1 to 2 minutes.
Add sandwiches, in batches if necessary. Place a heavy skillet atop sandwiches. Cook over medium-low heat for 6 to 8 minutes or until bottoms are toasted. Using hot pads, carefully remove top skillet.
Turn sandwiches and top again with skillet. Cook for 6 to 8 minutes more or until bottoms are toasted.
Prep 15 minutes
Cook 15 Mintues