Rich and Savory Gluten-Free Mushroom Quiche Recipe

Ingredients

For the Gluten-Free Pie Crust

3/4 cup plus 2 tablespoons tapioca flour, plus additional for dusting
3/4 cup cornstarch
1/4 cup plus 2 tablespoons superfine brown rice flour
1/4 cup gluten-free oat flour
2 teaspoons granulated sugar
1/4 teaspoon sea salt
1 1/2 teaspoons xanthan gum
1 cup cold salted butter, diced
3 large eggs

For the Egg Wash

1 large egg, beaten
1 tablespoon water

For the Mushroom Filling

1 tablespoon vegetable oil
1 pound oyster mushrooms, stems trimmed and large caps halved or quartered
1 pound white mushrooms, thinly sliced
Salt, to taste
Freshly ground white pepper, to taste
1 tablespoon unsalted butter
2 small shallots, minced
1 tablespoon chopped fresh thyme
3/4 cup shredded Comté or Emmental cheese, divided

For the Custard Filling

2 cups whole milk, divided
2 cups heavy cream, divided
6 large eggs, lightly beaten and divided
Freshly grated nutmeg, optional
3 teaspoons salt, divided
1/4 teaspoon white pepper, divided

Directions

Step 1: Combine the Dry Ingredients

In a large mixing bowl, whisk together the tapioca flour, cornstarch, brown rice flour, gluten-free oat flour, sugar, sea salt, and xanthan gum until evenly combined.

Step 2: Make the Gluten-Free Dough

Add the cold diced butter to the flour mixture. Work it into the dry ingredients with a pastry cutter or your fingertips until the mixture resembles coarse crumbs.

Add the 3 eggs and mix until a cohesive dough forms. Shape the dough into a disk, wrap it tightly, and refrigerate for at least 30 minutes.

Step 3: Shape the Crust

Lightly dust a work surface with tapioca flour. Roll the chilled dough into a large circle that will fit the bottom and sides of a 9-inch springform pan or deep-dish quiche pan.

Carefully transfer the dough to the pan. Press it evenly against the bottom and sides, repairing any cracks with small pieces of dough as needed. Refrigerate the shaped crust for 15 minutes.

Step 4: Apply the Egg Wash

Whisk the beaten egg and water together in a small bowl. Brush a light, even layer of egg wash over the chilled crust. Set the prepared crust aside.

Step 5: Cook the Mushrooms

Preheat the oven to 325°F.

Heat the vegetable oil in a large skillet over medium-high heat. Add the oyster mushrooms and sliced white mushrooms. Season them lightly with salt and white pepper.

Cook for about 5 minutes, stirring occasionally, until the mushrooms begin to soften and release their moisture.

Step 6: Finish the Mushroom Filling

Reduce the heat to medium. Add the unsalted butter, minced shallots, and chopped thyme.

Continue cooking for 10 to 12 minutes, stirring frequently, until the mushrooms are tender and most of the released liquid has evaporated. Taste and adjust the salt and white pepper as needed. Remove the skillet from the heat and allow the filling to cool slightly.

Step 7: Add the First Mushroom Layer

Sprinkle 1/4 cup of the shredded cheese evenly over the bottom of the prepared crust. Spread half of the mushroom mixture over the cheese.

Step 8: Prepare the First Custard Batch

Place 1 cup whole milk, 1 cup heavy cream, and 3 lightly beaten eggs in a blender. Add 1 1/2 teaspoons salt, 1/8 teaspoon white pepper, and a pinch of freshly grated nutmeg, if using.

Blend on high speed for about 1 minute, or until the custard is frothy and thoroughly combined.

Step 9: Pour the First Custard Layer

Carefully pour the first custard batch over the mushrooms in the prepared crust. Sprinkle another 1/4 cup of cheese over the custard, then distribute the remaining mushroom mixture evenly over the cheese.

Step 10: Prepare the Second Custard Batch

Combine the remaining 1 cup whole milk, 1 cup heavy cream, and 3 lightly beaten eggs in the blender. Add the remaining 1 1/2 teaspoons salt, 1/8 teaspoon white pepper, and another pinch of nutmeg, if using.

Blend for about 1 minute, or until frothy and completely combined.

Step 11: Finish Assembling the Quiche

Slowly pour the second custard batch into the quiche shell. Sprinkle the remaining 1/4 cup shredded cheese evenly over the top.

Step 12: Bake the Quiche

Place the quiche pan on a baking sheet to catch any drips. Bake for approximately 1 hour 30 minutes, or until the top is deeply golden brown and the center is just barely set.

The custard should retain a slight wobble in the center when the pan is gently shaken.

Step 13: Cool and Unmold

Remove the quiche from the oven and allow it to cool until very warm. This resting period helps the custard finish setting and makes the quiche easier to slice.

If desired, use a serrated knife to carefully trim any excess crust flush with the top edge of the pan. Gently release and remove the springform ring.

Step 14: Slice and Serve

Cut the warm quiche into wedges with a sharp knife. Serve it on its own or pair it with a green salad, roasted asparagus, or fresh seasonal fruit.

Notes

Using both oyster mushrooms and white mushrooms gives the filling a more interesting combination of flavor and texture. Cook the mushrooms until most of their moisture has evaporated to prevent excess liquid from affecting the custard.

Comté cheese contributes a rich, nutty flavor. Emmental is a slightly milder and sweeter alternative that also melts beautifully.

Fresh thyme complements the earthy mushrooms and creamy custard. Chop it finely so its flavor is evenly distributed throughout the filling.

For the best gluten-free results, verify that the oat flour, cornstarch, tapioca flour, brown rice flour, xanthan gum, and all other packaged ingredients are appropriately labeled gluten-free. Prevent cross-contact when preparing the recipe for someone with celiac disease or gluten sensitivity.

Allow the baked quiche to cool before cutting it. Slicing it immediately after baking may cause the warm custard to lose its shape.

For overnight preparation, let the baked quiche cool completely. Leave it unmolded, cover it, and refrigerate overnight. When ready to serve, cut the quiche into wedges, arrange them on a baking sheet, and warm them in a 350°F oven for about 10 minutes or until heated through.

Alternatively, refrigerate the cooled quiche in an airtight container for up to 4 days. Reheat individual slices or the entire quiche in a 325°F oven for approximately 15 minutes, or until thoroughly warmed.