Bring the chicken or vegetable stock to a boil in a large deep saucepan.

Add the polenta in a thin steady stream and whisk until the mixture comes to a boil.

Reduce the heat to low.

Cook, stirring with a long-handled wooden spoon or whisk, for 10 minutes until the polenta is soft and thick.

Stir in the butter and ½ cup of the grated Parmesan.

Grease a deep 8-inch square cake pan.

Line the base and sides with parchment paper.

Pour the polenta mixture into the pan.

Cover it and refrigerate for 3 hours to firm up.

Preheat a 5- or 6-quart air fryer to 400˚F for 3 minutes.

Turn the polenta out from the pan and cut it into 20 chips.

Place the chips on a tray and scatter the remaining grated Parmesan over them, turning to coat all sides.

Then, spray the chips generously with cooking spray.

Carefully pull out the air fryer pan and basket.

Spray the basket with oil and place the chips in the basket.

Slide the pan and basket back into the appliance.

Keep the temperature set at 400˚F and set the timer for 15 minutes.

Cook, turning the chips halfway through the cooking time until they are golden brown and crisp.

Serve the polenta chips sprinkled with salt flakes.