Overnight Merguez and Mushroom Strata

published Dec 23, 2021
christmas
Overnight Merguez and Mushroom Strata Recipe

At its most basic, strata is stale bread, egg custard, and cheese. After that, it’s pretty much a choose-your-own adventure. This version has a harissa-spiced custard, merguez sausage, and mushrooms.

Serves8 to 10

Prep30 minutes

Cook1 hour 10 minutes

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mushroom strata casserole
Credit: Photo: Christopher Testani; Food Styling: Jesse Szewczyk

I first fell in love with strata while watching the movie The Family Stone. There’s a specific kind of pain that comes with accidentally ruining a dish you’re particularly proud of, and the scene where Sarah Jessica Parker drops her strata? I felt that. 

As tragic as that moment in the movie was, it led to many strata variations in my kitchen. It’s one of my go-to recipes for a few reasons — it can be prepped ahead of time, it’s adaptable to whatever you happen to have on hand, and it’s basically a savory bread pudding that’s just a warm breakfast hug. 

At its most basic, strata is stale bread, egg custard, and cheese. After that, it’s pretty much a choose-your-own-adventure. This version has a harissa-spiced custard, merguez sausage, and mushrooms.

Much like a frittata, a strata is versatile enough to absorb all of the sad, slightly wilted veggies in your fridge and make them new again. Leftover vegetables can be added right in, but it’s a good idea to cook any fresh vegetables beforehand. We don’t want a soggy strata, so give any leafy greens, mushrooms, squash, or any kind of vegetable that gives off a bit of water a cook beforehand to remove some of that liquid.  

If merguez isn’t your favorite, or you can’t find it locally, you can use bacon, ham or breakfast sausage; just cook any raw proteins before adding to the strata. I love andouille sausage in this, and using the pre-cooked version makes prep even faster — chop it into bite-sized pieces and add it straight in. Or, you can skip the meat all together and add in more of your favorite vegetables and fresh herbs, like rosemary, thyme or basil. 

Overnight Merguez and Mushroom Strata Recipe

At its most basic, strata is stale bread, egg custard, and cheese. After that, it’s pretty much a choose-your-own adventure. This version has a harissa-spiced custard, merguez sausage, and mushrooms.

Prep time 30 minutes

Cook time 1 hour 10 minutes

Serves 8 to 10

Nutritional Info

Ingredients

  • 2 tablespoons

    salted or unsalted butter

  • 1 (16- to 18-ounce) loaf

    unsliced levain or sourdough bread

  • 1

    small or 1/2 medium yellow onion

  • 3 cloves

    garlic

  • 8 ounces

    cremini mushrooms

  • 4

    medium scallions

  • 8 ounces

    Gruyère cheese

  • 12 ounces

    uncooked merguez sausage

  • 1 tablespoon

    olive oil, plus more as needed

  • 1 1/2 teaspoons

    kosher salt, divided

  • 1 teaspoon

    freshly ground black pepper, divided

  • 8

    large eggs

  • 1 1/2 cups

    whole milk

  • 1 cup

    heavy cream

  • 2 tablespoons

    harissa sauce, such as Mina

Instructions

  1. Let 2 tablespoons salted or unsalted butter sit at room temperature until softened.

  2. Meanwhile, if you are using fresh bread, arrange a rack in the middle of the oven and heat the oven to 250ºF (skip this toasting step if you are using stale bread and just cut or tear it). Cut or tear 1 (16- to 18-ounce) loaf levain bread into rough 1-inch pieces (10 to 12 cups). Place in an even layer on a rimmed baking sheet. Bake until just starting to dry out but not browned, about 10 minutes. Set aside to cool.

  3. Coat a 9x13-inch baking dish with half of softened butter, then coat a sheet of aluminum foil with the remaining butter.

  4. Dice 1 small or 1/2 medium yellow onion (about 3/4 cup) and finely chop 3 garlic cloves. Trim and cut 8 ounces cremini mushrooms about 1/2-inch thick (about 2 cups). Thinly slice 4 medium scallions (about 1/2 cup). Grate 8 ounces Gruyère cheese on the large holes of a box grater (about 2 cups). Remove the casings from 12 ounces merguez sausage.

  5. Heat 1 tablespoon olive oil in a large skillet over medium heat until shimmering. Add the sausage, use a wooden spoon to break it up into bite-sized pieces, and cook until cooked through and browned, 4 to 7 minutes.

  6. Transfer the sausage with a slotted spoon to a large bowl. Remove all but 2 tablespoons of grease from the pan. (If there is less than 2 tablespoons grease, make up the difference with olive oil.) Add the onion and garlic to the skillet and cook over medium heat, stirring occasionally, until the onion is starting to soften, about 3 minutes.

  7. Add the mushrooms, season with 1/2 teaspoon of the kosher salt and 1/2 teaspoon of the black pepper, and increase the heat to medium-high. Cook, stirring occasionally, until the liquid the mushrooms release is mostly evaporated and they begin to brown, 6 to 8 minutes. Meanwhile, place 8 large eggs, 1 1/2 cups whole milk, 1 cup heavy cream, 2 tablespoons harissa sauce, the remaining 1 teaspoon kosher salt, and remaining 1/2 teaspoon black pepper in a large bowl and whisk to combine.

  8. When the mushrooms are ready, transfer to the bowl with the sausage. Add the bread, half of the cheese, and half of the scallions, and toss to combine. Transfer to the baking dish and spread into an even layer. Pour the milk mixture evenly over everything, then sprinkle with the remaining cheese. Cover the baking dish tightly with the foil butter-side down and refrigerate for at least 1 hour or up to 24 hours. Cover and refrigerate the remaining scallions.

  9. Arrange a rack in the middle of the oven and heat the oven to 375°F. Let the strata sit at room temperature while the oven heats.

  10. Bake covered for 30 minutes. Uncover and bake until the eggs are set, the top is browned, and the edges are crispy, about 20 minutes more. Sprinkle the reserved scallions on top and let cool for 10 minutes before serving.

Recipe Notes

Milk: You can substitute whole milk for the heavy cream and use 2 1/2 cups total.

Meat: The merguez sausage can be substituted with your favorite protein or omitted completely. Cook any raw meats like bacon or breakfast sausage before adding to the strata.

Cheese: Any cheeses that melt, such as cheddar, fontina, havarti, and Monterey Jack, can be used in place of the Gruyère.

Vegetables: Up to 1 1/2 cups cooked vegetables, such as baby spinach, kale, or asparagus can be added to the strata mixture before baking. Cook any fresh vegetables before adding to the strata to help remove some of their water content and prevent sogginess. Frozen spinach can be thawed and squeezed to remove excess water first.

Make ahead: The strata can be assembled and refrigerated unbaked for up to 24 hours.

Storage: Leftovers can be refrigerated in an airtight container for up to 4 days. Alternatively, cut into individual slices, wrap tightly in aluminum foil, and freeze in an airtight container for up to 2 months. Reheat in a 350ºF oven (keep the frozen portions wrapped in foil) until warmed through, 20 to 25 minutes. Alternately, you can reheat in the microwave: cover a piece of strata with a damp paper towel and heat on high for 2 to 3 minutes.