Preheat oven to 180°C. Whisk softened unsalted butter and curd in a bowl till smooth. Add the cookie mix. Stir to form a soft dough. Add walnuts / toppings as desired. Scoop tablespoon size cookie dough balls, 2 inches apart, on to a lined tray. Bake for 12 minutes OR for 15 minutes if you prefer a crisper cookie. Allow cookies to cool for 2 minutes before removing from the tray.