Place sauerkraut in 3- to 4-quart slow cooker. Place beef brisket on sauerkraut. (If brisket includes packet of spices, sprinkle spices over brisket.)
Cover and cook on Low heat setting 9 to 11 hours.
Remove beef from cooker; place on cutting board. Cut beef into slices. To serve, spread 1 tablespoon dressing on each toast slice. Using slotted spoon to remove sauerkraut from cooker, top 8 slices toast with 1/2 cup sauerkraut each. Top sauerkraut with beef slices and cheese slice. Top with remaining toast.
Note: This recipe was tested in slow cookers with heating elements in the side and bottom of the cooker, not in cookers that stand only on a heated base. For slow cookers with just a heated base, follow the manufacturer’s directions for layering ingredients and choosing a temperature.