Add the hot sauce, Worcestershire, molasses, garlic, onions and tomato sauce to a slow cooker and stir to mix the ingredients together.
Sprinkle the chicken breasts liberally with salt and pepper and add to the slow cooker, coating evenly with the sauce. Cover and cook on low until the chicken is tender, 4 to 6 hours. Transfer the cooked chicken to a large bowl and shred using 2 forks. Return the shredded chicken to the slow cooker and toss to coat with the sauce.
Place 4 to 6 celery leaves on each bottom bun and pile 1/2 cup of the shredded chicken on top. Smear the top bun with Blue Cheese Aioli and place on top of the chicken.
Blue Cheese Aioli:
Combine the blue cheese, mayonnaise, thyme and garlic together in a small bowl and stir well.