Nutty-flavoured Gruyère and sautéed crimini and shiitake mushrooms find the perfect home nestled atop a homemade crust in this satisfying tart. Enjoy it for a savoury breakfast, or cut a slice and serve alongside a fresh salad for dinner. No matter when it's consumed, you'll be hard pressed to stop at a single piece!

Mushroom, Gruyère & Thyme Tart
makes 1 tart

Crust Ingredients:
2 cups all purpose flour
1/3 cup finely grated Parmesan
1 teaspoon Kosher salt
1 cup unsalted butter (2 sticks), chilled
1/4 cup ice water, plus
1-2 additional tablespoons (as needed) 

Filling Ingredients:
1 tablespoons olive oil
3 tablespoons butter, divided
1 red onion, thinly sliced
2 cloves garlic, minced
1-1/2 lbs assorted mushrooms (such as crimini, shiitake, and oyster), cleaned and thinly sliced
1/2 teaspoon Kosher salt
1/4 cup Marsala wine
1 tablespoon fresh thyme
2 eggs
1/3 cup half-and-half
4 oz. Gruyère cheese, grated
2 oz. Parmesan, grated
Mixed baby greens (for serving) 

Directions:

1. Make the crust by whisking together the flour, Parmesan, and salt. Cut the cold butter into 1/4" slices and gradually add it to the flour mixture, tossing often to coat, breaking the butter into smaller pieces while mixing. Gradually add the ice water into the flour mixture, about 1 tablespoon at a time, tossing to obtain an even consistency. The dough will be shaggy with small pieces of butter evident.

2. Knead the dough a couple times just until it comes together to make a ball. Flatten the ball into a disc roughly 1" thick and wrap it in plastic wrap. Chill the dough in the refrigerator for at least one hour or overnight. 

3. In a large skillet, heat the olive oil and 1 tablespoon butter together over medium heat. Add the onion and cook, stirring often until the onion begins to brown, roughly 10 minutes. Transfer the cooked onion to a large mixing bowl and set aside. 

4. In the same skillet, heat the remaining 2 tablespoons of butter and add the garlic, cooking for about 1-2 minutes, or until nicely fragrant. Add the sliced mushrooms and salt, and cook, stirring occasionally, until the pan begins to become dry and the mushrooms begin to brown, about 13-15 minutes.

5. Add the Marsala wine to the mushrooms and cook until no liquid remains, about 5-7 minutes. Add the fresh thyme and cook for another minute. Remove from heat and set aside. 

6. Preheat the oven to 375°F. Combine the mushrooms with the onions and stir in the eggs, half-and-half, Gruyère, and Parmesan. Pour the filling into the chilled tart crust, and bake in the oven for 35-45 minutes, or until the crust is golden and the egg has set. 

7. Slice and serve immediately. Pair with a side of mixed baby greens.