If using, heat olive oil in a large skillet over medium heat. Add thinly sliced green bell pepper and onion. Sauté for 5-7 minutes until softened and slightly caramelized. Remove from skillet and set aside.

In the same skillet, add the cooked shredded chicken. Pour in the buffalo sauce and stir to coat the chicken thoroughly. Heat the chicken and sauce mixture over medium heat for 3-5 minutes, allowing the sauce to warm and thicken slightly, clinging to the chicken.

Lay the slices of provolone or mozzarella cheese over the hot buffalo chicken mixture in the skillet. Cover the skillet with a lid or foil and let it sit for 2-3 minutes, allowing the cheese to melt completely and become gooey.

While the cheese melts, prepare the hoagie rolls. Split them lengthwise but not all the way through. Lightly toast the inside of each roll under a broiler for 1-2 minutes until golden, or in a dry skillet.

Carefully open each toasted hoagie roll. Using a spatula, transfer a generous portion of the cheesy buffalo chicken mixture into each roll. If you sautéed vegetables, layer them on top of the chicken.

Drizzle a generous amount of ranch or blue cheese dressing over the filling of each sandwich. Garnish with chopped fresh chives or green onions if desired.

Serve immediately with extra dressing and buffalo sauce on the side for dipping.