Mushroom & Leek Quiche Recipe

1. Make dough

Combine flour, sugar, and salt in a bowl. Cut in cold cubed butter with a pastry blender or two forks until mixture resembles coarse crumbs with some pea-sized pieces remaining.

2. Sprinkle cold water, 1 tablespoon at a time, tossing with a fork, until dough comes together when pressed (about 3 tablespoons). Do not overwork. Form into a disk, wrap in plastic, and chill at least 30 minutes (up to 2 days).

3. Blind-bake crust

Preheat oven to 375°F (190°C). Roll chilled dough on a lightly floured surface to fit a 9-inch (23 cm) tart or quiche pan with removable bottom. Transfer dough to pan, trim and crimp edges. Prick bottom lightly with a fork. Chill 10 minutes.

4. Butter the pan lightly, line crust with parchment and fill with pie weights or dried beans. Bake 15 minutes, remove weights and parchment, then bake 5–8 minutes more until crust is set and just starting to brown. Reduce oven to 350°F (175°C). Let cool slightly.

5. While crust chills, heat butter and olive oil in a large skillet over medium heat until shimmering.

6. Add sliced leeks and a pinch of salt. Sauté 4–5 minutes until softened and beginning to caramelize at edges.

7. Add sliced mushrooms and increase heat to medium-high. Cook, stirring occasionally, until mushrooms release their moisture and it's evaporated and edges are golden brown, about 6–8 minutes.

8. Stir in minced garlic and thyme and cook 30–45 seconds until fragrant. Season with 3/4 teaspoon salt and 1/2 teaspoon black pepper. Taste and adjust seasoning. Remove from heat and let cool slightly.

9. In a medium bowl whisk together eggs, half-and-half, heavy cream, Dijon mustard, 1/2 teaspoon salt, and 1/4 teaspoon black pepper until smooth and slightly frothy.

10. Scatter 3/4 cup of the grated Gruyère evenly over the bottom of the prepared crust.

11. Spread the sautéed leeks and mushrooms in an even layer over the cheese in the crust.

12. Pour the egg mixture gently over the filling, leaving a small space at the top. Sprinkle the remaining 1/2 cup of Gruyère over the top.

13. Place the quiche on a baking sheet and bake at 350°F (175°C) for 30–35 minutes, or until the center is just set (a slight jiggle is fine) and the top is golden. If the crust edges brown too quickly, tent with foil.

14. Remove from oven and let rest 10–15 minutes to finish setting before slicing.

15. While quiche rests, place mixed salad greens in a bowl. Drizzle with 1 tablespoon extra-virgin olive oil and 1 teaspoon sherry or red wine vinegar. Season with 1/8 teaspoon salt and 1/8 teaspoon pepper, toss gently to coat.

16. Slice the quiche and serve warm or at room temperature alongside the dressed mixed greens.