How to Make Upside-Down Cream of Mushroom Tartlets

Upside-down tartlets have gone viral on social media as a shareable snack hack. This recipe uses store-bought puff pastry paired with a cozy season cream of mushroom soup-inspired filling. The filling combines sliced mushrooms and a classic duxelles of minced mushrooms and shallots. It is supplemented with Gruyère, heavy cream, and either sour cream or crème fraîche to balance the rich pastry. Working with puff pastry requires keeping the cold butter intact to ensure flaky layers. Most components can be made ahead, with the mushroom filling ready up to three days in advance.