1Spray 4- to 4 1/2-quart slow cooker with cooking spray. In 10-inch skillet, cook sausage over medium-high heat until no longer pink; drain. Stir in leeks and thyme.
2In slow cooker, layer half the sweet potatoes, sausage mixture and cheese. Repeat with remaining sweet potatoes and sausage mixture. Pour apple juice over top; sprinkle with remaining cheese.
3Cover; cook on High heat setting 2 1/2 to 3 hours or until sweet potatoes are tender.