With something so simple, the flavors are so intense. I love making mushroom duxelles and putting them into a vessel, such as deviled eggs. Duxelles is a finely minced/chopped mixture of mushrooms, often times cooked with shallots and thyme, sautéed in butter and reduced to a paste-like consistency.
Here we have Maitake Mushroom Duxelles in Deviled Eggs with Mornay Sauce. Mornay sauce is just Béchamel sauce with Gruyère cheese.