Broccoli au gratin, or simply broccoli gratin, is a cheesy broccoli casserole dish. A side dish or an entree, it combines layers of cheese sauce and crisp-tender [broccoli](https://www.masterclass.com/articles/how-to-cook-broccoli-how-to-steam-broccoli-and-roasted-broccoli-recipe), according to a culinary technique called gratin, which involves topping a dish with panko breadcrumbs, cheese, or melted butter before baking it under a broiler to achieve a crispy brown crust. While a strong cheddar cheese and [Parmesan cheese](https://www.masterclass.com/articles/a-guide-to-using-parmesan-cheese) are classics for this dish, you can also use Gruyère cheese or Emmental cheese for a more sophisticated flavor profile. \n\nYou can also make au gratin by substituting broccoli with another vegetable, such as leeks, green beans, cauliflower, zucchini, sweet potatoes, [butternut squash](https://www.masterclass.com/articles/how-to-peel-and-cut-a-butternut-squash-plus-10-butternut-squash-recipes), onions, or [Brussels sprouts](https://www.masterclass.com/articles/oven-roasted-brussels-sprouts) for a new veggie and cheese combination. Usually, broccoli au gratin serves as a side dish alongside a protein, such as [pork chops](https://www.masterclass.com/articles/how-to-cook-tender-and-juicy-pork-chops), roasted chicken, or [steak](https://www.masterclass.com/articles/aaron-franklins-tips-for-grilling-a-perfect-steak). Alternatively, you can mix a protein into the broccoli au gratin itself—for example, diced ham or crumbled bacon—to make it an entrée.\nBroccoli au gratin combines broccoli with cheese and a white sauce for a crisp-tender veggie dish.