Place the stock into a medium pot and bring to the boil over high heat.  

Slowly start adding the polenta while mixing with a whisk until combined. Turn the heat down to low and stir with a wooden spoon for 2 minutes, for it to start to thicken. 

Add the salt, rosemary sprigs and pepper. Stir to mix through, then add the milk and stir until it starts bubbling. Add the butter and mix until melts. Cook while stirring for 10 minutes. 

Stir through 1 cup of the parmesan cheese and continue to cook for 5 minutes until creamy. 

Transfer the polenta into a medium size baking tray, lined with baking paper. Flatten with a spatula and place another sheet of baking paper on top. Place in fridge to set for at least 4 hours until cool, or preferable overnight. 

Carefully remove the polenta from the tray and cut into 2cm long strips and then across into 5-6 cm chip size.  

Place the chips into an air fryer and spray with the olive oil. Cook at 220°C for 20mins until golden brown and crispy. 

For the Truffle Mayo: place all the ingredients into a mixing bowl and mix until combined.  

Serve parmesan polenta chips warm with the truffle mayo. Garnish with the remaining Parmesan.