Cut the steak into pieces 2" wide pieces, then add them into a bowl or zip-top bag along with olive oil and a few spoonfuls of cajun seasoning, enough to well coat the steak. Marinade them for at least 30 minutes, ideally overnight.
Soak the skewers in water before using (if using wood skewers) for at least 30 minutes.
Make the garlic parmesan butter on the stove or in a bowl in the microwave. Start by melting the butter and garlic together, then add cajun seasoning and the grated parmesan. Mix well until it's incorporated, then remove from the heat and add the fresh parsley.
Thread the marinated steak onto the skewers, packing them closely together to ensure they stay juicy as they cook. Preheat the air fryer (if your model requires you to do so) to 400 degrees.
Baste the skewers on both sides with the butter mixture. Cook the skewers, a few at a time, into the air fryer basket and cook for about 8-10 minutes, or until the internal temp reaches your desired doneness.
As they cook baste them with the garlic parmesan butter, flipping them once. I like to hit them with more garlic parmesan butter once they are done cooking.