In a small bowl, combine the seasonings, salt, pepper, garlic powder, and paprika.
Prepare the spread for the hoagie rolls by combining mayo and ketchup together.
In a large skillet, sauté the sliced mushrooms, peppers and onions with 1 Tbsp butter on medium high heat.
Season with 1/3 of the seasoning mixture and cook the vegetables for about 3-4 minutes, or until they are tender and lightly caramelized. Once tender remove from the skillet and set them aside.
Add the sliced chicken and oil to the skillet and cook on medium high heat for about 4-5 minutes, or until the chicken is cooked through. Sauté the chicken with the rest of the seasoning blend.
Once the chicken is cooked, add back in the veggies and mix to combine.
Turn off the heat. Layer slices of provolone cheese over the chicken and veggie mixture. Cover the skillet with a lid to allow the cheese to melt perfectly.
While the cheese melts, toast your hoagie rolls to a golden brown in a separate skillet or in the oven. Once toasted, spread your prepared sauce generously onto each bun.
With a spatula or spoon, scoop the cheesy Philly mixture onto the toasted hoagie rolls, evenly dividing the mixture between the four buns. (If you are not enjoying them all immediately, do not add the mixture to the buns to avoid soggy buns.)
Serve your Chicken Philly Sandwiches immediately while it is still hot. Pair with your favorite sides and enjoy.