Chef notes

While a simple scrambled or sunny side up egg always makes a nice addition to breakfast, a frittata provides more of a creative expression. While a traditional omelet hides the ingredients it’s filled with, a frittata lets you put the featured ingredients on display. And it can be a great way to use up leftovers or showcase seasonal ingredients, like we did in this sheet-pan version. For a lovely autumnal frittata, I added delicata squash, mushrooms and goat cheese.

While frittatas can be made in a saute pan on the stovetop or in the oven, probably the easiest way to make one for a crowd is in a sheet pan. You’ll need to cook ingredients such as onions, root vegetables, squash and asparagus before adding to your egg mixture. Leafy greens like spinach or watercress can be added directly to the egg mixture and will cook completely.

Besides the quick cooking time (it comes together in under 20 minutes), the advantage of using a sheet pan to make your frittata is that you can slice it into perfect portions for a breakfast sandwich. Thanks to the addition of flavorful seasonal produce, you won’t need much else on your sandwich except for a light schmear of butter or a dollop of ketchup or hot sauce.

If you’re planning to use this frittata for meal prep, place the squares on a baking sheet and place in the freezer until frozen. Then transfer the frittata squares to an airtight container. To reheat, place a piece of frittata on a baking sheet in a 350 F oven for 10 minutes.

Technique Tip: If you’re making the frittata to serve at brunch and want to streamline the cooking time, bake the mushrooms and squash in advance. Let them cool to room temperature and then transfer to an airtight container until the next day.

Swap Option: Most vegetables and leftover meats will work in this recipe. Just make sure that they’re sliced to a thickness of about 1/4 inch or they may not cook evenly. Instead of the goat cheese, try using 1 cup of shredded cheddar or Monterey Jack.

Ingredients

2 cups sliced baby bella mushrooms
1 small delicata squash, halved, seeded and sliced into 1/4-inch half moons
3 tablespoons extra-virgin olive oil, divided
1 small onion, peeled and diced
10 large eggs, room temperature

1/2 cup whole milk
1 (4-ounce) log plain goat cheese, softened
1/2 teaspoon sea salt
1/2 teaspoon freshly ground black pepper

Fulfilled by

Preparation

Preheat the oven to 375 F.

Arrange the mushrooms and squash pieces evenly on an 18-by-13-inch sheet pan. Drizzle with 2 tablespoons of olive oil and bake for 10 minutes, until slightly tender. Transfer to a plate to cool.

Meanwhile, heat the remaining 1 tablespoon olive oil in a large sauté pan over medium heat. Add the onion and cook for 2 to 3 minutes, until softened. Let cool.

In a large bowl, whisk together the eggs, milk, goat cheese, salt and pepper. Add the cooked onions to the egg mixture, then pour onto the sheet pan, adding the mushrooms and squash evenly on top. Carefully transfer the pan to the oven and bake until the edges are just set and the frittata is golden around the edges, 17 to 18 minutes.

Let the frittata cool for about 5 minutes, then cut into 12 squares (a pizza wheel works great for this). Use a spatula to transfer the squares from the pan to a plate or platter for serving. Leftovers can be stored in an airtight container in the refrigerator for up to 2 days or frozen for up to 3 months.