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Horizontal image of a white pie plate with a baked egg dish next to silverware on a towel.

Mushroom and Gruyere Crustless Quiche

  • Author: Fanny Slater
  • Total Time: 1 hour, 10 minutes
  • Yield: 4-6 servings 1x


This crustless quiche cuts back on the carbs, but loads up on earthy mushrooms, nutty Gruyere, and oniony leeks for loads of flavor.


  • Nonstick cooking spray
  • 1 tablespoon unsalted butter
  • 3 tablespoons olive oil, divided
  • 2 cups mixed mushrooms (such as shiitake, oyster, and cremini), stemmed and thinly sliced
  • 2 leeks, white and light green parts, thinly sliced
  • 1/2 cup thinly sliced fennel bulb, fronds reserved and roughly chopped
  • 3/4 teaspoon coarse salt, divided
  • 1/2 teaspoon freshly ground black pepper, divided
  • 12 large eggs
  • 1/2 cup half-and-half
  • 2 teaspoons chopped fresh thyme, plus more for garnish
  • 1 cup grated Gruyere cheese, divided
  • 1/2 cup grated fontina cheese


  1. Preheat the oven to 350°F and spray a 9-by-13-inch baking pan or casserole dish with nonstick cooking spray.
  2. In a large skillet over medium-high heat, melt the butter and heat 2 tablespoons of the olive oil. Add the mushrooms and saute, tossing occasionally until lightly browned, for about 3-5 minutes.
  3. Add the remaining olive oil and the leeks, fennel, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper. Cook, stirring frequently, until the leeks become slightly translucent and the mixture is very fragrant, about 5 minutes. Remove the pan from the heat and allow the veggies to cool to room temperature.
  4. In a large mixing bowl, whisk the eggs with the half-and-half, remaining 1/4 teaspoon salt, 1/4 teaspoon pepper, and the thyme. Fold in the mushroom mixture, half of the gruyere, and the fontina. Pour into the prepared baking dish. Sprinkle the remaining 1/2 cup gruyere on top.
  5. Bake until the top is lightly golden brown and the eggs are set, about 30-35 minutes (the internal temperature should read 160°F when checked with a thermometer).
  6. Remove from the oven. Allow the frittata to rest in the pan so the ingredients can set, about 10 minutes. Slice, garnish with the fennel fronds and a few fresh thyme leaves if you like, and serve warm or at room temperature.
  • Prep Time: 15 minutes
  • Cook Time: 45 minutes
  • Category: Vegetarian
  • Method: Baking
  • Cuisine: Breakfast and Brunch

Keywords: crustless quiche, frittata, mushroom, gruyere