Place the sliced onions and bell peppers in the bottom of the slow cooker to form an even layer.
Lay the chicken breasts on top of the vegetables, drizzle with olive oil, and sprinkle with Italian seasoning, garlic powder, onion powder, smoked paprika, salt, and pepper.
Pour the chicken broth around the sides of the slow cooker, then cover and cook on low for 6–7 hours or on high for 3–4 hours, until the chicken is tender.
Remove the cooked chicken to a cutting board and shred it with two forks into bite sized pieces.
Return the shredded chicken to the slow cooker, stirring it into the peppers, onions, and cooking juices. Leave on warm while you prepare the rolls.
Preheat the oven broiler. Spread the hoagie rolls with butter, place on a baking sheet, and toast until lightly golden.
Fill each toasted roll with the chicken Philly mixture, top with provolone cheese, and broil for 1–2 minutes until the cheese is melted and bubbly. Serve warm.