Put vegetable stock in a medium saucepan and bring to a simmer over medium heat. Slowly whisk in instant polenta until incorporated, lower the heat right down and cook for 10 minutes, stirring frequently.
Stir in butter, half a cup of parmesan cheese, salt, and pepper to the polenta mixture until the mixture has no lumps.
Transfer to a large rectangular pan lined with parchment paper and use a spatula to spread the mixture evenly. Refrigerate for an hour or until set.
Tip polenta upside down onto a chopping board and cut into chunky sticks, around 2.5x 8cm (1" x 3"). Spray or brush fries on each side with cooking oil.
Spray the air fryer basket with cooking oil and preheat to 400˚F. Line basket with fries, ensuring there is space between each one. Bake for 7 minutes, then flip fries over and bake for another 5 minutes or until the polenta fries and golden and crisp.
Remove from basket and sprinkle with remaining parmesan. Serve with aioli or dip of choice.
Plate, serve, and enjoy!