Prep Time::15 mins
Cook Time::20 mins
Total Time::35 mins
Servings::6 servings
Ingredients
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12 ounces cremini mushrooms, such as Baby Bella®
1/2 red onion, sliced vertically
1 tablespoon olive oil
1 tablespoon unsalted butter
2 tablespoons low-sodium soy sauce
1 teaspoon dried thyme
2 garlic cloves, minced
salt and freshly ground black pepper to taste
1/2 (17.3 ounce) package frozen puff pastry, thawed
1 1/2 cups shredded Gruyere cheese
1 large egg, beaten
1 teaspoon dried thyme, or as needed for garnish (optional)
Directions
Preheat the oven to 400 degrees F (200 degrees C). Line a baking sheet with parchment paper.
Cut mushrooms into 1/4-inch-thick slices (don’t cut too thinly).
Heat olive oil and butter in a large skillet over medium heat. Add mushrooms and onion and cook, stirring occasionally, until mushrooms are golden and onions are soft and translucent, 6 to 8 minutes.
Stir in soy sauce, thyme, and garlic and cook until fragrant, 30 to 60 seconds. Season with salt and pepper; set aside.
Unfold puff pastry sheet onto a lightly-floured work surface. Gently pat down or roll out dough with a rolling pin into a 10×10-inch square. Using a sharp knife, score a line about 1/2 inch from all edges to create a border, being careful not to cut all the way through. Use a fork to generously prick pastry sheet all over inside the border.
Transfer puff pastry to the baking sheet, and brush the borders with beaten egg. Evenly spread Gruyere cheese inside the border, and top with mushroom mixture.
Bake until tart is puffed and lightly browned, 10 to 12 minutes. Garnish with additional thyme, and serve warm.
Cook's Note:
If you’re unable to use Gruyere, Swiss cheese is a decent substitute, but won’t quite be as tasty as the Gruyere.