- Preheat oven to 375 degrees.
- Place puff pastry rounds in a single layer on a parchment-lined baking sheet and refrigerate while mushrooms cook.
- In a large skillet, heat oil over medium-high.
- Add shallot and cook, stirring, until soft, 3 minutes.
- Add mushrooms and cook, stirring, until soft and browned, 10 minutes.
- Season with salt and pepper.
- Stir in thyme and remove skillet from heat.
- Lightly oil 6 jumbo muffin cups.
- Divide mushroom mixture and cheese among cups,
- then top each with a chilled pastry round.
- Bake until pastry is golden brown and puffed, about 25 minutes, rotating pan halfway through.
- Run a small knife around cups to loosen tartlets.
- Place a rimmed baking sheet or large plate over pan and invert to release tartlets.
- Sprinkle with more thyme.
- Serve warm.
Upside-down Mushroom Tartlets





