Prepare Apples: In a large bowl, combine the sliced apples with lemon juice, brown sugar, granulated sugar, cinnamon, and nutmeg (if using). Toss until the apples are well coated.
Add to Slow Cooker: Transfer the apple mixture to the slow cooker. Dot the top with pieces of butter and drizzle the vanilla extract over the apples.
Cook: Cover and cook on low for about 4-6 hours or on high for 2-3 hours, until the apples are tender.
Serve: Once done, stir gently and serve warm. They’re great on their own or served over ice cream, pancakes, or oatmeal!