We doubled up on the mushroom filling for this savory galette. First, we blitzed criminis (also called baby bellas), then the shallots and herbs in the food processor into a spread reminiscent of duxelles (a French mushroom paste). The mushroom mixture gets caramelized in a skillet until the flavor is super concentrated, then mixed with sharp cheddar and cream before being spread across buttery free-form pie dough, which also comes together in the food processor for easy cleanup. (If you have the grating insert for your food processor, you can use it to coarsely grate the cheese as well!)
The second hit of ’shrooms comes from wild mushrooms, which you’ll scatter on top of the tart in big, meaty pieces. We’ve called for king trumpets and oysters, but you could use whatever you find at your local store, such as maitake, shiitake caps, or enoki.
Baking this savory mushroom galette on parchment paper keeps the crispy pastry crust from browning too quickly and makes it easy to transfer from baking pan to platter, while an egg wash brushed onto the folded edges gives it a party-ready sheen. Serve warm or at room temperature, cut either into small squares as a cocktail hour appetizer or larger pieces for a dinner party side dish or vegetarian main.