Caramelized Onion & Mushroom Tart | YumAndJoy

Caramelized Onion & Mushroom Tart

Why You’ll Love This Recipe

This caramelized onion and mushroom tart is a rich, savory dish that combines flaky, golden puff pastry with deep, umami-packed flavors. The combination of sweet, thyme-infused caramelized onions, earthy mushrooms, and creamy Gruyere cheese makes this tart a perfect appetizer or light main course. Elegant yet easy to make, it’s great for dinner parties, brunch, or cozy nights in.

Ingredients

(Tip: You can find the complete list of ingredients and their measurements in the recipe card below.)

  • All-butter puff pastry (thawed if frozen)
  • Onions (medium, thinly sliced)
  • Shiitake or cremini mushrooms (sliced)
  • Garlic (minced)
  • Fresh thyme
  • Gruyere cheese (grated)
  • Beef stock (for depth of flavor)
  • Sherry (or dry white wine)
  • Ghee or butter
  • Egg (for egg wash)

Directions

Prepare the Filling

  1. Caramelize the Onions: Heat 2 tablespoons of ghee or butter in a skillet over medium-low heat. Add sliced onions and cook, stirring occasionally, for 20-25 minutes until golden and caramelized.
  2. Cook the Mushrooms: Add the remaining tablespoon of butter, along with the sliced mushrooms and thyme. Sauté for 5-7 minutes until softened.
  3. Deglaze the Pan: Pour in the sherry and beef stock, scraping up any browned bits. Let it simmer until most of the liquid evaporates. Stir in minced garlic and cook for 1 more minute. Remove from heat and let cool slightly.

Assemble the Tart

  1. Preheat Oven: Set oven to 400°F (200°C). Line a baking sheet with parchment paper.
  2. Prepare the Puff Pastry: Roll out the thawed puff pastry onto the baking sheet. Lightly score a 1-inch border around the edges with a knife (without cutting through).
  3. Add the Toppings: Sprinkle half the Gruyere cheese over the pastry. Spread the caramelized onion and mushroom mixture evenly, then top with the remaining cheese.
  4. Brush with Egg Wash: Beat the egg with a splash of water and brush the edges of the pastry.

Bake & Serve

  1. Bake: Bake for 20-25 minutes until the pastry is golden brown and crispy.
  2. Cool & Serve: Let the tart cool slightly before slicing. Garnish with extra thyme and serve warm.

Servings and Timing

  • Servings: 8
  • Prep Time: 20 minutes
  • Cook Time: 50 minutes
  • Total Time: 1 hour 10 minutes

Variations

  • Cheese Swap: Try Swiss, Parmesan, or goat cheese for a different flavor.
  • Vegan Option: Use dairy-free puff pastry, omit the cheese, and swap butter for olive oil.
  • Extra Toppings: Add prosciutto, caramelized pears, or roasted garlic for added depth.
  • Gluten-Free: Use a gluten-free puff pastry or a cauliflower crust.

Storage/Reheating

  • Storage: Keep leftovers in an airtight container in the fridge for up to 3 days.
  • Reheating: Warm in a 350°F (175°C) oven for 5-7 minutes until crisp. Avoid microwaving, as it will soften the pastry.
  • Freezing: Freeze unbaked tart for up to 1 month. Bake from frozen, adding a few extra minutes.

FAQs

Can I use store-bought puff pastry?

Yes! Just ensure it’s made with butter for the best flavor.

How do I prevent a soggy crust?

Pre-bake the pastry for 5-7 minutes before adding toppings.

Can I make this tart ahead of time?

Yes! Assemble it and store it in the fridge for a few hours before baking.

What can I serve with this tart?

Pair it with a fresh salad, roasted vegetables, or a bowl of soup.

Can I use a different type of mushroom?

Yes! Portobello, button, or wild mushrooms all work well.

Can I use a different alcohol instead of sherry?

Yes! Dry white wine or balsamic vinegar can be used instead.

How do I get extra flaky pastry?

Chill the assembled tart for 10 minutes before baking.

Can I make mini versions of this tart?

Yes! Cut the puff pastry into smaller squares for bite-sized appetizers.

What if I don’t have Gruyere cheese?

Swiss cheese, Fontina, or even Brie work well as substitutes.

How do I caramelize onions faster?

Add a pinch of sugar and a splash of water to speed up the process.

Conclusion

This caramelized onion and mushroom tart is a flavorful, elegant dish that’s easy to make yet impressive to serve. The buttery, flaky pastry paired with the rich, cheesy filling makes it perfect for any occasion. Try different variations, serve it as an appetizer or main course, and enjoy every bite of this savory masterpiece!

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Caramelized Onion & Mushroom Tart

Caramelized Onion & Mushroom Tart


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  • Author: asma
  • Total Time: 1 hour 10 minutes
  • Yield: 8 servings 1x
  • Diet: Vegetarian

Description

This Caramelized Onion & Mushroom Tart is a savory showstopper! Featuring golden, flaky puff pastry topped with rich caramelized onions, sautéed mushrooms, thyme, and melted Gruyere cheese, this elegant dish makes a perfect appetizer or main course for any occasion.


Ingredients

Units Scale

For the Tart:

  • 1 (14 oz) package all-butter puff pastry, thawed
  • 1 egg, beaten (for egg wash)

For the Caramelized Onions & Mushrooms:

  • 2 medium onions, thinly sliced
  • 12 oz shiitake or cremini mushrooms, sliced
  • 3 tbsp ghee or butter
  • 2 cloves garlic, minced
  • 1 tbsp fresh thyme leaves
  • 1/4 cup sherry
  • 1/4 cup beef stock
  • 1 1/4 cups Gruyere cheese, grated

Instructions

  1. Preheat Oven: Preheat to 400°F (200°C). Line a baking sheet with parchment paper.
  2. Caramelize the Onions: In a large skillet, melt 2 tbsp butter over medium-low heat. Add sliced onions and cook for 20–25 minutes, stirring occasionally, until golden brown. Add sherry and cook for another 2 minutes. Remove from heat.
  3. Sauté the Mushrooms: In the same skillet, melt 1 tbsp butter over medium heat. Add mushrooms, garlic, thyme, and cook for 5–7 minutes until tender. Stir in beef stock and cook for another 2 minutes. Remove from heat and combine with caramelized onions.
  4. Prepare the Pastry: Roll out the puff pastry on the prepared baking sheet. Lightly score a 1-inch border around the edges without cutting through. Brush the border with the beaten egg.
  5. Assemble the Tart: Sprinkle half of the Gruyere cheese over the pastry. Spread the caramelized onion and mushroom mixture evenly, then top with the remaining cheese.
  6. Bake: Bake for 20–25 minutes, or until the pastry is golden brown and crispy.
  7. Serve & Enjoy: Let cool slightly, then slice and serve warm.

Notes

  • Substitute Gruyere with Swiss or Parmesan if preferred.
  • For a vegetarian version, use vegetable stock instead of beef stock.
  • Serve with a side salad for a light meal.
  • Prep Time: 20 minutes
  • Cook Time: 50 minutes
  • Category: Appetizer, Main Course
  • Method: Baking
  • Cuisine: French-Inspired
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