Place the potato, beans and zucchini in a heavy-based saucepan of boiling salted water and boil for 15–20 minutes or until the potato is tender. Drain in a strainer and set aside to cool in the strainer.
Place the cooled vegetables in a food processor and process until smooth. Transfer to a large bowl and stir in the egg, Grana, garlic, basil and salt and pepper to taste. Refrigerate fo