Mushroom Onion Puff Pastry
Ingredients:
- 3 tbsp. butter, divided
- 2 medium onions, halved and sliced thinly
- 1/4 tsp. salt
- 1/4 tsp. black pepper
- 1/4 cup sherry or white wine
- 1/4 cup beef stock
- 12 oz. shiitake or cremini mushrooms, or combo of both
- 2 cloves garlic
- 1 tbsp. fresh thyme leaves, divided use
- 14 oz. package all-butter puff pastry, thawed
- 1 1/4 cups grated Gruyere cheese
- 1 whisked egg, for egg wash
Directions:
- Place a large, heavy-bottomed skillet over medium-high heat, and add in 1 1/2 tablespoons of the butter. Once melted, and the skillet is hot, add the sliced onions plus a sprinkle of salt and black pepper. Cook the onions, stirring frequently, until cooked down and deeply caramelized, about 20 minutes.
- Once caramelized, pour in the sherry and allow it to bubble up for a moment. Next, add in the beef stock and allow it to bubble up. Reduce the heat to low and spoon the onions into a dish or bowl to hold and to cool.
- To the same skillet, add the remaining 1 1/2 tablespoons of butter and bring the heat back up under it to medium-high once more. Add in the sliced mushrooms plus a sprinkle of salt and pepper and sauté the mushrooms for about 5 to 7 minutes, until golden. Stir in the garlic and sprinkle in 1 teaspoon of the fresh thyme into the mushrooms. Cook for 4 to 5 minutes and then turn off the heat. Spoon the mushrooms into a separate bowl or dish lined with a paper towel to cool.
- Preheat oven to 400 F.
- To prepare the tart, place a piece of parchment paper the size of your baking sheet in front of you on a work surface and sprinkle lightly with flour. Place the thawed puff pastry sheet in front of you on the parchment and give it a gentle roll with a rolling pin, just enough to even the edges and make it roughly 10 by 13 inches, and 1/8 inch thick.
- Create a border for your tart by using a sharp knife to gently score the pastry about 1/2 inch from the edge, all the way around, taking care not to cut all the way through the pastry. Use a fork to prick the center of the puff pastry a few times to help it bake flat.
- Lightly sprinkle 3/4 cup of the cheese on the bottom, then top with the sautéed mushrooms and the caramelized onions. Sprinkle over this another 1/2 cup of cheese.
- Gently egg wash the border you created and bake the tart for 26 to 30 minutes or until a deep, golden brown.
- Allow the tart to cool on the baking sheet for 10 minutes and then sprinkle over the remaining 2 teaspoons of the thyme leaves as garnish and cut the tart into pieces.
