1Spray 3- to 4-quart slow cooker with cooking spray. In slow cooker, mix beets, apple juice, vinegar, garlic and salt.
2Cover; cook on High heat setting 3 to 4 hours.
3Meanwhile, sprinkle walnuts in ungreased heavy skillet. Cook over medium heat 5 to 7 minutes, stirring frequently until nuts begin to brown, then stirring constantly until nuts are light brown. Set aside.
4In small bowl, mix cornstarch and water; stir into beets in slow cooker. Cook uncovered 5 to 10 minutes longer or until sauce has thickened. Sprinkle with cheese and toasted walnuts.