I've used Japanese and Kent pumpkin for this recipe, but Butternut should also work as it is a sweet variety. If you like your fudge sweet, use the amount of caramel recommended. If you prefer your sweets not as rich, half the caramel should do the trick. Agar agar powder is a seaweed-based (vegetarian) jelly setter that's widely available from Asian supermarkets. 1 hour chilling time additional.