Food & Cooking Recipes Appetizers Upside-Down Mushroom Tartlets 3.1 (296) 12 Reviews By Martha Stewart Editors Martha Stewart Editors Facebook Instagram Twitter Website An article attributed to "Martha Stewart Editors" indicates when several writers and editors have contributed to an article over the years. These collaborations allow us to provide you with the most accurate, up-to-date, and comprehensive information available.The Martha Stewart team aims to teach and inspire readers daily with tested-until-perfected recipes, creative DIY projects, and elevated home and entertaining ideas. They are experts in their fields who research, create, and test the best ways to help readers design the life they want. The joy is in the doing. Editorial Guidelines Updated on June 12, 2017 Print Rate It Share Share Tweet Pin Email Prep Time: 20 mins Total Time: 45 mins Yield: 6 Cut these into quarters for pretty yet simple hors d'oeuvres, or serve them with a crunchy green salad for lunch or a light supper. Ingredients 1 sheet frozen puff pastry, thawed and cut into six 3-inch rounds 1 tablespoon extra-virgin olive oil, plus more for muffin pan 1 large shallot, diced small 1 pound cremini mushrooms, sliced Coarse salt and ground pepper 2 teaspoons fresh thyme leaves, plus more for serving ¾ cup grated Gruyere cheese (2 ounces) Directions 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. Rate it Print