Start by slicing your hoagie rolls in half and spreading butter on each cut side. Toast them in a skillet, cut side down, over medium heat until lightly browned—just 1–3 minutes. If you’re using the garlic mayo mix, spread it on after toasting for a rich, savory layer.
Slice your chicken thinly and season with garlic powder, salt, and pepper. Heat the oil in your skillet over medium-high heat, then add the chicken in a single layer. Cook for about 2–3 minutes per side, until golden and cooked through. Remove from the skillet and set aside.
In the same skillet, toss in the sliced onions and bell peppers. Sauté them for about 4–6 minutes, stirring occasionally, until tender and lightly caramelized. Once they’re soft and fragrant, return the chicken to the pan and mix everything together.
Reduce the heat to low and lay provolone slices over the hot chicken-and-veggie mix. Cover the skillet with a lid or foil and let the cheese melt for about 1–3 minutes. Once gooey and melty, scoop the mixture into your toasted rolls and serve immediately.