Heat oven to 200C/180C fan/gas 6. Mix together the garlic, anchovy, lemon juice, two-thirds of the Parmesan and parsley. Put half in a small bowl, mix with the yogurt and set aside. Mix the other half in a large bowl with the mince and onion, then season. Shape into 4 burgers and place on a roasting tray, then cook for 15-20 mins, until cooked through.