Food & Cooking Recipes Appetizers Upside-Down Mushroom Tartlets 3.1 (296) 12 Reviews By Martha Stewart Test Kitchen Martha Stewart Test Kitchen The recipes developed by our test kitchen team have undergone a rigorous process of development and testing, ensuring that every element is optimal, from ingredient amounts to method and cooking time. This process includes triple-testing recipes to ensure they meet our high standards. The many stellar cooks and food editors who have been part of our team include Sarah Carey, Lucinda Scala Quinn, Jennifer Aaronson, Shira Bocar, Anna Kovel, Greg Lofts, Riley Wofford, Lauren Tyrell, and Lindsay Leopold. 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