If you’re looking for Real Food™ then I’d go with stuffed mushroom caps. Super easy, vegetarian adaptable, absolutely delectable, and definitely reheatable.
Can’t remember the source, but here’s what I made for thanksgiving.
Trim cremini or portobello mushrooms and chop stems. Cook crumbled sausage in olive oil until it begins to brown, then add stems and chopped onion and garlic. Mix with cooked rice. Bind with Parmesan. Spoon the stuffing into the mushroom caps and bake until tender. (They only cooked for ~20/25 minutes at 375º. I used medium portobello caps, wild rice, and Vermont Cheddar instead of Parmesan. I also actually cooked them in cupcake pans and used a fork to remove them! That kept the bottoms from getting rubbery or burnt, and the trapped moisture kept them juicy!)
If some sort of desert, Peppermint Bark is surprisingly simple to craft in volume. Think 9“x13“x.25” for under $10. (Tips from experience: I didn’t layer, just went with classic one layer dark, top layer white. I’d also suggest mixing the peppermint extract into both types of chocolate, along with mixing the crushed candy into the white chocolate instead of sprinkling it. Unlike the specified 7, 12 oz. of bittersweet chocolate was just enough to cover the pan. Spreading the chocolate can be done much more easily by hand than with a spatula after covering the chocolate with saran-wrap as it looses it’s heat very quickly and the plastic won’t melt or stick. [EmpressPixie is to be credited for that last trick!])