Best French Onion Cabbage Gratin Recipe

Cabbage is having a moment, and this French onion-inspired recipe is our favorite way to transform the humble vegetable into a wow-worthy side. It’s the perfect indulgent side to take any weeknight dinner from good to oh so great. To make it, crisp browned cabbage wedges are smothered in a rich Gruyère sauce packed with jammy caramelized onions and topped with buttery breadcrumbs. It’s not a quick side dish, but it’s worth every second it takes—here’s everything you need to know:

The cabbage:
Plain green cabbage is best for this recipe. I don’t recommend using a Savoy or Napa cabbage, since these varieties have more delicate leaves and will not hold their shape or sear as easily in the pan. Red cabbage is also not a great move, since the color may bleed into the sauce, turning it a strange beige pink. A smaller cabbage is also better here; if the cabbage wedges are too large, they might not fit easily into the pan.

The caramelized onions:
Caramelized onions take a bit of time, but they’re very easy to make. Patience is key. Don’t be tempted to turn up the heat to “speed up” the process: you’ll only end up with undercooked onions with browned (maybe slightly burnt) edges. If at any point you notice the onions starting to fry around the edges, turn the heat down slightly on the pan and add a splash of water (about a tablespoon). The water will prevent the onions from burning, while actually helping them cook faster (for more on this, check out this article, where I use the same technique with mushrooms!).

Make ahead & storage:
The caramelized onions can be made up to 3 days in advance and stored in an airtight container in the refrigerator. Any leftovers can also be stored in the refrigerator in an airtight container for up to 3 days.

Did you try making this? Let us know how it went in the comments!