If eggs are considered vegetarian in your crowd (they are not in mine), a slab quiche or kuku could work well. With kuku you can also have pita, hot sauce, and yogurt on the side for sandwich-making.
I often make french-style lentil salad for these types of things, adding quinoa to bulk it up a bit.
I like @Phoenikia’s vegetarian moussaka suggestion — it used to be one of my mom’s regular party dishes, always a hit.
A similar option is vegetarian shepherd’s pie, using beans or lentils or eggplant as the base.
Or ratatouille if you don’t want a carby topping.
@adawks Phyllo pie suggestion reminded me of a Serbian friend’s cheese pie / gibanica (also made with spinach or meat) — like this.
Another easy crowd-pleaser is chana (chickpea) masala — serve with slider buns or crostini or over a base of basmati rice (chana pulao would be a biryani-like variation).
