slice of sausage, spinach and egg casserole

I have been making some variation of this breakfast casserole since this past Christmas morning, when I made Andrew Feinberg’s broccoli frittata, which was very well received (by the four adults sitting at the table).

What differentiates Andrew’s frittata from others is the cooking method, and in particular, the unusually low oven temperature — 250ºF — which prevents the custard from becoming dry and granular.

Like many frittata recipes, Andrew’s starts on the stovetop and finishes in the oven. In the recipe included below, the eggs cook entirely in the oven, moving it out of the frittata territory, making it more of an egg bake or a casserole (though there’s no cream or milk).

This recipe should be used as a guide and tailored to your tastes and preferences. I like a little bit of greens, a little bit of cheese, a little bit of onion, and a little bit of sausage, which makes the casserole feel a bit more substantial and precludes the need for cooking other breakfast meat on the side, which is especially nice when entertaining.

Here’s a rough framework:

The Makings of A Very Nice Breakfast Casserole

  • Eggs: Estimate about 2 per person.
  • Salt: A good rule of thumb: 1/2 teaspoon kosher salt for every 4 eggs.
  • Something green. I like spinach, because it’s so low maintenance. No need to cook it — simply toss it with the hot sausage and onions, the heat of which will gently wilt it. Other options: roasted asparagus or broccoli, finely chopped Swiss chard or kale, etc.
  • Cheese: I like Gruyère or Fontina. For 12 eggs, 4 ounces of grated cheese is about right.
  • Onions: If you have the time to caramelize or near-caramelize an onion, do it. Otherwise, chopped scallions or chives will add that nice allium flavor, while also providing more green color.
  • Sausage: I love hot Italian sausage here. The spices in the sausage flavor the custard, and the subtle spiciness is nice. Also: spinach + sausage is always a good match.

Breakfast casseroles or egg bakes are great for — wait for it — breakfast or brunch, especially when entertaining. But they also make great, low-key dinners, and the format can be used to clean out the odds and ends in your vegetable bins. Cold or re-heated, the leftover casserole makes a fine lunch on subsequent days, too.

This is how I like to make this breakfast casserole: Start by browning the sausage.
Hot Italian sausage browning in a pan stovetop.

Pour it over a heap of spinach in a colander — this serves to both gently wilt the spinach and drain off excess fat and moisture.
Sausage and spinach in colander in sink.

Caramelize or nearly caramelize an onion, if you wish.
Onions caramelizing in a pan stovetop.

Transfer the onion to the colander as well.
Caramelized onion on top of sausage and spinach in colander in sink.

Toss to combine and further wilt the spinach.
Sausage, onions, spinach all tossed together.

Transfer to a 9×13-inch pan and cover with grated cheese. (Love this 9×13-inch USA Pan.)
A 9x13-inch pan with sausage, spinach, cheese, and caramelized onions.

Beat 12 eggs.
12 cracked eggs in a bowl with salt

12 eggs, whisked

Pour the eggs over top.
A 9x13-inch pan filled with eggs, cheese, sausage, spinach, and onions.

Bake until custard is just set.
A very nice breakfast casserole with eggs, Gruyere, sausage, spinach, and onions.

An up-close shot of a breakfast casserole with eggs, Gruyere, sausage, spinach, and onions.

slice of sausage, spinach and egg casserole

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slice of sausage, spinach and egg casserole

Sausage, Egg, and Cheese Casserole with Spinach

  • Author: alexandra
  • Prep Time: 20 minutes
  • Cook Time: 40 minutes
  • Total Time: 1 hour
  • Yield: 6 to 8 servings


Use the proportions below as a guide. You can omit the sausage to make it vegetarian. If you want to scale it up or down, a good rule of thumb is 1/2 teaspoon kosher salt for every 4 eggs.


  • 2– to  4-oz baby spinach (I typically use 3 ounces)
  • 1 tablespoon olive oil, plus more as needed
  • 0.50.75 lb. hot Italian sausage
  • 1 yellow onion, thinly sliced or diced
  • 1.5 teaspoons kosher salt, plus more as needed
  • 4 oz. grated cheese, I like Gruyère or Fontina
  • 12 eggs
  • freshly cracked black pepper to taste.


  1. Heat oven to 250ºF. Place spinach in a large colander and set it in the sink. Grease a 9×13-inch pan lightly with butter or with nonstick spray.
  2. In a medium skillet over medium-high heat, heat the oil till it shimmers. Cook the sausage till it browns and is nearly cooked through, about 5 minutes. Break it up with a spoon or a spatula as it cooks. Spoon the sausage over the spinach in the colander in the sink. Return the skillet to the stove top, add a little bit more oil to the pan if necessary, and set it over medium heat. Add the onions. Season with salt. Cook the onions till they begin to caramelize, 7 to 10 minutes. Spoon the onions over the sausage and toss with a spatula or large spoon to gently wilt the spinach. Transfer the spinach-sausage mixture to the prepared pan. Spread the cheese over top.
  3. Break the eggs into a large bowl, season with the 1.5 teaspoons salt and fresh cracked pepper to taste. Beat with a whisk until the eggs are well blended. Pour the eggs into the pan. Season with more pepper to taste. Transfer pan to the oven and bake for 30-40 minutes, rotating the pan halfway through. Start checking at 30 minutes, then every 5 minutes thereafter till it’s done — depending on your oven and the material of the pan you are using, it may take more or less time to cook.
  4. Remove pan from the oven, and let it cool for 5 minutes before serving.
  • Category: Breakfast
  • Method: Oven
  • Cuisine: American

Keywords: egg, casserole, sausage, cheese, spinach