This slow cooker apple crisp combines tender, spiced apples with a buttery, crunchy oat topping. Toss sliced apples with lemon juice, brown sugar, cinnamon, and vanilla, then layer them in the slow cooker. Mix flour, oats, brown sugar, cinnamon, and cold butter to create a crumbly topping, and spread it over the apples. Cover with a paper towel under the lid to keep the topping crisp, then cook on high for 1.5 hours. Remove the towel and cook for an additional 30-60 minutes. Serve warm with…