Good party food can be eaten without plates or flatware. This means it should be stab-able, scoop-able, or come pre-loaded onto an edible delivery system. You won’t be able to stab anything with an endive leaf, but it makes an excellent scoop, and a truly elegant delivery system.
If you’ve never had the pleasure of enjoying endive, it’s pretty fun, as far as non-psychoactive leaves go. It’s crunchy at the base and delicate at the tips, with a mild, slightly bitter flavor that complements cheeses, spreads, and salads. Its naturally occurring boat-like shape makes it a worthy vessel for any of the above, plus it just looks pretty. If that wasn’t enough, you and your guests can feel virtuous about eating a bunch of endive-based appetizers—anything you put on it becomes a salad! (It’s also easy to prep; just wipe the outermost leaves with a damp towel.)
As far as fillings, you can’t go wrong with cheese. Pimento cheese, drizzled with a little honey (garlic honey if you have it), and sprinkled with chives is a personal fave, as is blue cheese with pecans and dried cranberries. If you want something meatier, try little spoonfuls or chicken salad, chicken liver mousse, or smoked salmon spread. If you’d like to veer towards the veggie side of things, try loading it up with a tangy slaw or chopped salad; just make sure to include one non-veg component—like crumbled cheese, crispy prosciutto, or toasted nuts—to balance out all the freshness. You can also fan a whole bunch of leaves out beside a bowl of dip. It is a party, after all.