one of my favorite things to bake for a get-together at our house is alice waters' onion tart; it is full of deliciously caramelized onions and a perfectly flaky crust. it's easy to make and people love it- usually even if they don't love onions. also, it's the perfect division of labor recipe! matt makes the crust and i make the rest. yum.
i've mentioned waters' the art of simple food cookbook before. i highly recommend it if you are looking for no-fail, simple recipes.
(i've modified the recipe a bit to the way i make it, after finding it online here)