Toss together apples and cinnamon. Place in a slow cooker that has been sprayed with non-stick vegetable spray; set aside.
Combine oats, brown sugar, flour and butter; mix with a pastry cutter or fork until crumbly. Stir in pecans and toffee bits; sprinkle over apples.
Cover and cook on low setting for 4 to 6 hours. Top with whipped topping, if desired.