Broccoli au Gratin

published Sep 23, 2021
Broccoli au Gratin Recipe

A comforting bake of tender broccoli in a creamy sauce, topped with buttery breadcrumbs and Parmesan cheese.


Prep15 minutes

Cook45 minutes

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Broccoli au Gratin in casserole dish.
Credit: Photo: Kristin Teig | Food Stylist: Catrine Kelty

Broccoli is one of my favorite vegetables, because the fluffy florets trap in whatever seasonings and sauces you toss them with. A delicious way to eat broccoli is baking it in a smooth, velvety sauce flavored with generous handfuls of sharp cheddar cheese — also known as au gratin.

This broccoli au gratin is a bit like mac and cheese, with broccoli subbed in for the macaroni. Each bite has tender broccoli in a creamy, cheesy sauce with crunchy breadcrumbs, and it’s hearty enough to be a vegetarian main dish or served as a side to your favorite protein.

What Does au Gratin Mean? 

Au gratin simply means to top a dish with a browned crust using ingredients like cheese, breadcrumbs, eggs, or butter. Here, buttery panko breadcrumbs and grated Parmesan cheese meld as they cook in the oven, turning golden-brown, crunchy, and really comforting and satisfying.

Credit: Photo: Kristin Teig | Food Stylist: Catrine Kelty

How to Make Broccoli au Gratin

To make broccoli au gratin, start by cutting the broccoli, stems and all, into bite-sized pieces. Don’t waste those sweet stems — they’re delicious as long as you peel off the fibrous exterior first. Peel until you get from the stringy, darker outside to the smoother, lighter interior. When in doubt, peel more!

A lot of recipes have you blanch the broccoli first to pre-cook it and preserve its green color, but I’ve found you can skip that step — something I appreciate since I live where water conservation is important. Just toss the broccoli directly into the thick, creamy cheese sauce, where it will cook as it bakes. The gratin will come out of the oven bubbly and browned on top, but make sure to let it sit for a few minutes for the sauce to thicken up before serving.

Can I Use Frozen Broccoli? 

Yes! You can make broccoli au gratin with frozen broccoli as long as you thaw it first and, more importantly, get rid of some of the water clinging to the broccoli so it doesn’t water the sauce down. Gently squeeze the water out of the thawed broccoli, then pat any surface moisture off with towels. The frozen broccoli is now ready to use in the gratin.

Credit: Photo: Kristin Teig | Food Stylist: Catrine Kelty

What to Serve with Broccoli au Gratin

Broccoli au Gratin Recipe

A comforting bake of tender broccoli in a creamy sauce, topped with buttery breadcrumbs and Parmesan cheese.

Prep time 15 minutes

Cook time 45 minutes

Serves 6

Nutritional Info


  • Cooking spray or butter, for coating the baking dish

  • 1 1/2 pounds

    broccoli crowns (about 3 medium), broccoli florets, or frozen broccoli

  • 1/2

    medium yellow onion

  • 8 ounces

    sharp cheddar cheese (2 cups shredded), preferably white

  • 5 tablespoons

    unsalted butter

  • 3 tablespoons

    all-purpose flour

  • 1/2 teaspoon

    dry mustard, or 1 1/2 teaspoons Dijon mustard

  • 2 cups

    whole or 2% milk

  • 3/4 teaspoon

    kosher salt

  • 1/3 cup

    panko breadcrumbs

  • 2 tablespoons

    grated Parmesan cheese


  1. Arrange a rack in the middle of the oven and heat the oven to 425ºF. Coat an 8-inch square or other 2-quart baking dish with cooking spray or butter and place on a baking sheet.

  2. Cut 1 1/2 pounds broccoli crowns or florets into 1-inch pieces, and cut any large pieces of stalk crosswise into 1/2-inch-thick pieces (8 to 9 cups total). If using frozen broccoli, thaw 1 1/2 pounds according to package directions, gently squeeze out the excess liquid with your hands, and pat very dry with towels.

  3. Dice 1/2 medium yellow onion (about 3/4 cup). If needed, shred 8 ounces sharp cheddar cheese on the large holes of a box grater (about 2 cups).

  4. Melt 5 tablespoons unsalted butter in a Dutch oven or large pot over medium heat. Transfer 1 tablespoon into a small, heatproof bowl.

  5. Add the onion to the remaining butter in the pot and cook over medium heat, stirring occasionally, until softened, about 5 minutes. Sprinkle with 3 tablespoons all-purpose flour and 1/2 teaspoon dry mustard (or 1 1/2 teaspoons Dijon mustard) and stir constantly for 1 minute. While stirring constantly, slowly pour in 2 cups whole or 2% milk and stir until the flour is completely dissolved. Bring just to a full simmer over medium-high heat, stirring frequently.

  6. Add the cheddar and 3/4 teaspoon kosher salt, and stir until the cheese is melted and the sauce is bubbling. Remove the pot from the heat, add the broccoli, and stir until well-coated in the sauce. Transfer to the baking dish and spread into an even layer.

  7. Add 1/3 cup panko breadcrumbs and 2 tablespoons grated Parmesan cheese to the reserved bowl of melted butter and stir to combine. Sprinkle the gratin with the breadcrumb mixture.

  8. Keeping the gratin on the baking dish to catch any drips, bake until the broccoli is tender and the sauce is bubbling, about 30 minutes. If you’d like a browner top, broil until the breadcrumbs are golden-brown, 2 to 3 minutes more. Let cool for 10 minutes to let the sauce thicken before serving.

Recipe Notes

Make ahead: The sauce can be made up to 2 days ahead, cooled, and refrigerated in an airtight container. The broccoli can be cut and refrigerated up to 2 days ahead. Bring the sauce back to a simmer over medium heat before proceeding with the recipe.

Storage: Leftovers can be refrigerated in an airtight container for up to 4 days.