To the bowl of a slow cooker add: chicken, onion, garlic, broth and hot sauce. Cook on low for 6 hours.
Using two forks, shred chicken and stir mixture. Season with salt and pepper.
Place rinse romaine leaves among plates. Use a slotted spoon to remove chicken from crockpot, allowing as much liquid as possible to drip through and divide among lettuce leaves.
Drizzle with additional hot sauce if desired and sprinkle with blue cheese crumbles.