Start by slicing each of the hoagie rolls in half. Make sure not to cut all the way through; you want them to hold their shape. Spread a thin layer of butter on each side of the rolls.
Next, heat a large skillet over medium heat and place the hoagie rolls cut side down. Allow them to cook until they are lightly browned, about 1 to 3 minutes. Once toasted, remove the rolls from the pan and set them aside.
If you prefer a wetter sandwich, mix the mayonnaise and extra garlic powder now and spread it on the inside of each roll.
In the same skillet, add the vegetable oil and turn the heat to medium-high. Prepare your chicken breast by thinly slicing it into strips. Season the slices evenly with garlic powder, salt, and pepper.
Add the seasoned chicken strips to the skillet, making sure to spread them into a thin layer. Sear on the first side for 2 to 3 minutes until golden brown, then flip and continue cooking until no longer pink, which should take another 1 to 3 minutes.
Once the chicken is cooked, remove it from the skillet and set it aside. Now, add the sliced onions and bell pepper to the pan.
Let the vegetables sear for about 2 to 3 minutes, then stir and continue cooking until they are soft, which will take an additional 1 to 3 minutes.
Return the cooked chicken to the skillet with the onions and peppers. Stir them together, ensuring everything is well combined.
Reduce the heat to low and place the sliced provolone cheese over the top of the chicken and vegetables. Cover the skillet with a lid or foil, allowing the cheese to melt for about 1 to 3 minutes.
Finally, use a spatula to scoop the chicken and vegetable mixture into the toasted hoagie rolls. Serve immediately and enjoy your delicious Chicken Cheesesteaks!