Preheat the oven to 180°C / 350°F / gas 4. Prepare your lined tin.
Grate the parsnips and potato into a bowl and mix in the rosemary, garlic purée, lemon juice and 2 tsp of oil. Season with salt and pepper.
Line a baking tray with baking paper and grease the top. Using a star cookie cutter (or a shape of your choice), fill the star with your mixture, getting right into the corners and pushing it down with a spoon. I used the thin end of the spoon to really get into the corners.
Gently push the star out onto your tray. Repeat this until you have used up all the mixture.
Gently brush the top of the stars with the remaining oil. Sprinkle each star with parmesan cheese and place in the oven for about 25 minutes, until crisp and golden.
Serve warm as a canapé or with your Christmas dinner. Enjoy!