If you don't have a quiche pan, consider getting one. You really need a pan with straight sides to make a proper quiche, and once you know how good quiche is, you will make many of them.
Make your favorite non-sweet crust, and bake it "blind" in the pan. Which is to say, put a single crust in your quiche pan, prick it
liberally with a fork, cover it with buttered foil, buttered side down, then fill the pan with dried beans (to weigh down the crust) and bake it. You can reclaim the beans and use them again. Let the crust cool.
Peel and dice the eggplant, put into a colander, salt well and allow to sit for an hour. When the hour is up, squeeze the eggplant well, handful by handful, to remove the salty liquid that will accumulated.
Fry the sausage until done, and remove it from the pan to drain on paper towels.
Turn the heat up under the grease from the sausage and put in the eggplant,
sautéing it until it is golden. It will absorb all the grease. Bad for the arteries, but very tasty.
Beat together the eggs, cream, salt and pepper until well combined. Distribute the eggplant and sausage over the baked crust and pour the egg and cream mixture over it. Dot with small pieces of butter.
Bake in a 375º oven for 30 minutes. Test by sticking in a knife. When the blade emerges clean, the quiche is done.
Cool for twenty minutes, then cut and serve.