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Mushroom and Caramelized Onion Tart

The scent of caramelized onions always transports me back to my tiny Brooklyn apartment, where I first attempted this tart for a friend’s birthday. The aroma filled the entire building, and while I slightly charred the onions (oops!), the overall effect was magical. The savory mushrooms, sweet onions, and tangy chevre, all nestled in a buttery, flaky crust, created a symphony of flavors that was unforgettable. It’s a dish that speaks of comfort, elegance, and a touch of rustic charm.

Recipe Overview

Prep Time: 45 minutes
Cook Time: 45 minutes
Total Time: 1 hour 30 minutes
Servings: 6
Yield: 2 small tarts
Dietary Type: Vegetarian

Ingredients

Pastry:

1 cup all-purpose flour
1/4 cup unsalted butter, partially frozen
1/4 teaspoon kosher salt
2-3 tablespoons ice water

Filling:

2 tablespoons unsalted butter
1 tablespoon virgin olive oil, plus more as needed
1 lb cremini mushrooms, sliced
1/4 lb morel mushrooms, broken apart
3 sweet white onions, julienned
Kosher salt & freshly ground black pepper
6 ounces chevre cheese, room temperature

Equipment Needed

Food processor
Large sauté pan
Rolling pin
Parchment paper
Baking sheet
Pie weights or dried beans

Instructions

Preheat your oven to 400 degrees F (200 degrees C).
Prepare the pastry: In the bowl of a food processor, combine the flour, partially frozen butter, and salt. Pulse a few times to break the butter into small pieces. The mixture should resemble coarse cornmeal.
With the food processor running, slowly add the ice water, one tablespoon at a time, until the dough just comes together when squeezed. Be careful not to over-process, or the crust will be tough.
Gather the dough into a rectangle, wrap it tightly in plastic wrap, and refrigerate for 30 minutes. This allows the gluten to relax, resulting in a more tender crust.
While the dough chills, prepare the mushroom filling. Heat the butter and olive oil in a large sauté pan over medium-high heat.
Add the sliced cremini and broken morel mushrooms to the pan. Stir to coat them with the oil and butter. Then, spread the mushrooms out in a single layer and allow them to cook, undisturbed, for a couple of minutes. This helps them brown properly.
Stir the mushrooms once and redistribute them in the pan. Continue cooking in the same way – allowing them to sit undisturbed for a few minutes between stirs – until they are golden brown and have released most of their moisture. Remove the mushrooms from the pan and set aside.
Add the julienned onions to the same sauté pan. If the pan seems dry, add a little more olive oil. Sauté the onions over medium heat, stirring occasionally, until they are deeply caramelized and golden brown. This process will take at least 20-30 minutes, so be patient. Season with salt and pepper to taste.
Remove the chilled pastry dough from the refrigerator. Divide it in half.
On a lightly floured surface, roll out each piece of pastry into a long strip, approximately 4 inches by 8 inches.
Place the pastry strips on a baking sheet lined with parchment paper. Crimp the edges of the dough to create a raised rim. This will help contain the filling and give the tarts a rustic look.
Cover each tart with parchment paper and fill with pie weights or dried beans. This will prevent the pastry from puffing up during baking.
Bake the tarts for 15 minutes. Then, carefully remove the parchment paper and pie weights (or beans) and bake for another 5 minutes, or until the crust is lightly golden brown. Remove the tarts from the oven and let them cool slightly.
Reduce the oven temperature to 350 degrees F (175 degrees C).
Spread half of the chevre cheese evenly over the bottom of each tart. Then, top with half of the caramelized onions and half of the browned mushrooms.
Bake the tarts for another 15 minutes, or until the filling is heated through and the cheese is slightly melted.
Remove the tarts from the oven and let them cool for 5 minutes before serving.

Expert Tips & Tricks

For a deeper, richer flavor, add a splash of dry sherry or balsamic vinegar to the onions during the last few minutes of caramelizing.
If you can’t find morel mushrooms, you can substitute them with other wild mushrooms, such as shiitake or oyster mushrooms.
To prevent the bottom crust from becoming soggy, brush it with a thin layer of egg wash before adding the filling.
If the pastry starts to brown too quickly, tent it with foil.
Make the pastry ahead of time and store it in the refrigerator for up to 2 days, or in the freezer for up to 1 month.
Caramelize the onions a day ahead to save time. Store them in an airtight container in the refrigerator.

Serving & Storage Suggestions

To serve, cut each tart in half lengthwise and then into 6 equal pieces. Arrange the tart slices on a serving plate. Garnish with fresh herbs, such as thyme or parsley. The tarts are best served warm or at room temperature.

Leftover tarts can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, warm them in a 350 degrees F (175 degrees C) oven for 10-15 minutes, or until heated through. You can also reheat them in the microwave, but the crust may become slightly soggy.

Nutritional Information

Nutrient	Amount per Serving	% Daily Value
Calories	344.6 kcal	N/A
Calories from Fat	203 g	59%
Total Fat	22.6 g	34%
Saturated Fat	13.5 g	67%
Cholesterol	52.9 mg	17%
Sodium	227.9 mg	9%
Total Carbohydrate	25.9 g	8%
Dietary Fiber	2 g	7%
Sugars	4.8 g	19%
Protein	11.4 g	22%

Variations & Substitutions

Gluten-Free: Use a gluten-free all-purpose flour blend to make the pastry.
Dairy-Free: Substitute the butter in the pastry with a vegan butter alternative and use a dairy-free cream cheese or cashew cheese instead of chevre.
Vegan: In addition to the dairy-free substitutions, consider using a flax egg (1 tablespoon ground flaxseed mixed with 3 tablespoons water, let sit for 5 minutes) to help bind the pastry dough.
Seasonal: Try different types of mushrooms depending on the season, such as chanterelles in the fall or morels in the spring. You can also add other seasonal vegetables, such as asparagus or roasted butternut squash.
Cheese Variations: Experiment with different cheeses, such as goat cheese, Gruyere, or Fontina.

FAQs (Frequently Asked Questions)

Q: Can I use pre-made pie crust?
A: Yes, you can use pre-made pie crust to save time. Just make sure to use a high-quality crust for the best flavor and texture.

Q: How do I prevent the crust from shrinking during baking?
A: Chilling the dough before rolling it out, using pie weights during the first bake, and avoiding over-handling the dough will help prevent shrinking.

Q: Can I freeze the baked tart?
A: Yes, you can freeze the baked tart. Let it cool completely before wrapping it tightly in plastic wrap and foil. Freeze for up to 2 months. Thaw overnight in the refrigerator before reheating.

Q: What other herbs can I use besides thyme?
A: Rosemary, sage, or oregano would also pair well with the mushrooms and onions.

Q: The onions are burning before they caramelize. What am I doing wrong?
A: Reduce the heat to medium-low and add a tablespoon or two of water to the pan. This will help to deglaze the pan and prevent the onions from burning. Stir frequently.

Final Thoughts

This Mushroom and Caramelized Onion Tart is a guaranteed showstopper, whether you’re serving it as an elegant appetizer at a dinner party or enjoying a cozy weekend brunch. Don’t be intimidated by the steps – each one is simple and rewarding. I urge you to gather your ingredients, preheat your oven, and experience the magic of transforming humble ingredients into a culinary masterpiece. Share your creations and experiences, and who knows, maybe this tart will become a cherished memory for you too! And remember, a crisp, dry white wine, like a Chardonnay or Sauvignon Blanc, makes a delightful companion to this savory tart.

Mushroom and Caramelized Onion Tart Recipe