Caramelized Onion & Mushroom Tart is a savory pastry dish that combines sweet, caramelized onions with earthy mushrooms, all baked in a flaky crust. This tart is perfect as an appetizer, side dish, or even a light main course, and is sure to impress at any gathering.
Ingredients
For the Tart Crust:
- 1 1/4 cups all-purpose flour
- 1/2 teaspoon salt
- 1/2 cup unsalted butter (cold and cubed)
- 3-4 tablespoons ice water
For the Filling:
- 2 tablespoons olive oil
- 2 large onions (thinly sliced)
- 8 ounces mushrooms (sliced, such as cremini or button)
- 2 cloves garlic (minced)
- 1 teaspoon fresh thyme (or 1/2 teaspoon dried thyme)
- Salt and pepper (to taste)
- 1/2 cup heavy cream
- 2 large eggs
- 1/2 cup grated cheese (such as Gruyère or Parmesan)
Timing
Making Caramelized Onion & Mushroom Tart takes about 20 minutes for preparation and 35-40 minutes for cooking.
Instructions
Step 1: Prepare the Tart Crust
- Mix Dry Ingredients: In a mixing bowl, combine the flour and salt.
- Cut in Butter: Add the cold, cubed butter to the flour mixture. Using a pastry cutter or your fingers, work the butter into the flour until the mixture resembles coarse crumbs.
- Add Ice Water: Gradually add ice water, one tablespoon at a time, mixing until the dough comes together. Do not overmix.
- Chill Dough: Shape the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 30 minutes.
Step 2: Prepare the Filling
- Caramelize Onions: In a large skillet, heat the olive oil over medium heat. Add the sliced onions and a pinch of salt. Cook, stirring occasionally, for about 20-25 minutes until the onions are golden brown and caramelized.
- Add Mushrooms and Garlic: Stir in the sliced mushrooms and minced garlic. Cook for an additional 5-7 minutes until the mushrooms are tender and any liquid has evaporated. Add thyme, salt, and pepper to taste. Remove from heat and let cool slightly.
Step 3: Preheat Oven
- Preheat Oven: Preheat your oven to 375°F (190°C).
Step 4: Assemble the Tart
- Roll Out Dough: On a floured surface, roll out the chilled dough into a circle about 12 inches in diameter. Transfer to a 9-inch tart pan, pressing it into the edges. Trim any excess dough.
- Blind Bake Crust: Prick the bottom of the crust with a fork. Place a piece of parchment paper over the crust and fill it with pie weights or dried beans. Bake for 15 minutes. Remove the weights and parchment, and bake for an additional 5 minutes until lightly golden.
- Mix Egg and Cream: In a bowl, whisk together the heavy cream and eggs. Season with salt and pepper.
- Combine Ingredients: Spread the caramelized onion and mushroom mixture evenly over the tart crust. Pour the egg and cream mixture over the top, then sprinkle with grated cheese.
Step 5: Bake the Tart
- Bake: Bake the tart in the preheated oven for 25-30 minutes, or until the filling is set and the top is golden brown.
Step 6: Serve
- Cool and Slice: Allow the tart to cool for a few minutes before slicing. Serve warm or at room temperature. Enjoy your delicious Caramelized Onion & Mushroom Tart!

Nutritional Information
Here’s a quick overview of the nutritional content of Caramelized Onion & Mushroom Tart (per slice, based on 8 servings):
| Nutrient | Amount per Serving |
|---|---|
| Calories | 280 |
| Protein | 7g |
| Fat | 20g |
| Carbohydrates | 22g |
| Fiber | 2g |
| Sugar | 2g |
Tips for Customization
- Add Greens: Incorporate spinach or kale into the filling for added nutrition and color.
- Cheese Variations: Experiment with different cheeses like feta, goat cheese, or cheddar for unique flavors.
- Make It Vegan: Use a plant-based cream and egg substitute for a vegan version of the tart.
Conclusion
Caramelized Onion & Mushroom Tart is a flavorful and elegant dish that makes for a perfect appetizer or light meal. With its rich filling and flaky crust, this tart is sure to be a hit at any gathering. Enjoy this delightful recipe!
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