Place chicken in the bottom of a slow cooker and pour the sauce over top. Cook the chicken on high for 4 hours or low for 6 hours. When the chicken is cooked through, transfer to a plate and remove the bones. Shred the chicken using two forks and return to the slow cooker.
Slice the bread into 1 inch slices and brush both sides with olive oil. Turn the broiler on high. Place the bread slices on a baking sheet and toast under the broiler until crispy and golden. Turn the bread slices over and toast the other side. Remove from the oven and rub both sides of the toast with the garlic half. Return the toast to the baking sheet and top each slice with approximately 1/2 a cup of pulled chicken. Top each sandwich with one slice of provolone cheese and return the baking sheet to the oven.
Broil the sandwiches until the cheese is golden and bubbling, approximately 2-3 minutes. Transfer the sandwiches to a serving platter or plate and sprinkle with parmesan cheese and basil. Serve immediately.