Add them to a food processor with the rest (except potatoes and hard cheese)of the ingredients and blend until smooth. This makes around 240ml of pesto, so just use 3 tbsp for the potatoes and store the rest in an air tight container for up to 5 days.
In a bowl, mix the potatoes and pesto and add to a lightly oiled baking tray. Put in a preheated oven at 200C for 25 minutes.
Take the potatoes out of the oven and sprinkle over the parmesan and salt and pepper and put back in the oven for 15 minutes.