Line slow cooker with crockpot liner or spray with nonstick cooking spray. Add diced apples, sugar free syrup, xylitol, lemon juice, and seasonings. Toss until well coated.
In a bowl combine ingredients for topping until crumble forms. Sprinkle evenly over the top of the apple mixture in the slow cooker.
Cover and cook on low for 8 hours or high for 4 hours.