The best steakhouses have a side dish game that’s as strong as their dry-aged beef selection—if you stop to think about it, a steakhouse meal is the alterna-Thanksgiving for the other 364 days of the year. Just like I could go with or without the turkey on Thanksgiving Day, I often get distracted away from the steak when presented with a lineup of iceberg wedges draped in blue cheese and bacon; crocks of crispy breadcrumbed mac and cheese; scalloped potato gratin, bubbling away in a gallon of cream sauce; and bowls of garlicky creamed spinach.
Specifically, it’s those last two sides that make my heart skip a beat in more ways than one. Maybe in this case, you’d be forgiven for assuming my Thanksgiving menu is sponsored by the PC Police. (That’s Pro-Cream Police, in case you’re wondering, and no, it doesn’t exist in real life. Unless you consider me the founding member.) Or maybe the Pro-Potato Police, because for a few years, it seemed impossible to cut either mashed potatoes or potato gratin from the roster. They were both too good in their own right.
But there’s no law against bringing a new root vegetable to the table—after all, sweet potatoes and regular potatoes co-exist in Thanksgiving harmony without any slap fights or side-eye glances. And since we know all too well that everything tastes better when simmered in a little cream sauce, I’ve devised the ultimate solution. My steakhouse-inspired gratin uses whisper-thin slices of celery root instead of potatoes, and bulks up with a whole bunch (two bunches, actually) of spinach, thus fulfilling the creamed spinach requirement that no one knew they needed at Thanksgiving.
And if we can talk about getting those roots down to whisper-thin thickness for a minute… I know, mandoline slicers are terrifying. They’re used infrequently, bulky to store, and worse, you run the risk for slicing the tips of your fingers even if you’re attempting to use one of the useless plastic food guards that come with every model. Let me introduce you to the De Buyer Kobra slicer (yes, I’m calling it out by name and no, no one’s paying me to do it.) It’s small and thin so it fits in a drawer, adjusts slicing thickness like a champ, and stays crazy sharp for years. Ditch that plastic pusher and grab a cut-proof glove, and you’re in business.
If you aren’t already seduced by the promises of creamy vegetables and persuaded by my sales pitch for the perfect useful slicer, the knowledge that this is a fantastic make-ahead dish for Thanksgiving. Par-bake the gratin for 45 minutes, then refrigerate until it’s ready to make its big debut. Then throw it back in the oven to get that final gorgeous browned Gruyere crust. The turkey will get its spotlight stolen for sure.
Celery Root and Spinach Gratin
Prep time: 30 minutes
Cook time: 1 hour 30 minutes
Total time: 2 hours (can be made in advance and finished the day you plan to serve)
Makes 8-10 servings
Adapted loosely from Williams-Sonoma
- unsalted butter or nonstick baking spray
- 1 cup heavy cream
- 1 cup whole milk
- 1 teaspoon kosher salt
- 1/2 teaspoon freshly ground black pepper
- 1 tablespoon olive oil
- 2 large shallots, minced
- 2 large garlic cloves, minced
- 1 large leek, white and light green parts only, cleaned and sliced into paper-thin half-moons
- 2 bunches fresh spinach, rinsed well and roots trimmed
- 2 pounds celery root, peeled and sliced 1/8-inch thick
- 1/2 pound (8 oz.) Gruyère cheese, coarsely shredded
Preheat the oven to 375°F. Butter a 9-by-13-inch baking dish or spritz with nonstick baking spray.
Whisk the cream, milk, salt, and pepper together in a medium mixing bowl.
Heat the olive oil in a wide, high-sided sauté pan over medium-low heat until shimmering. Add the shallot, garlic, and leek and cook, stirring occasionally, for about 5 minutes until the shallot and leek are soft and translucent.
Add the spinach in large handfuls, stirring constantly to wilt the spinach before adding the next handful.
When the spinach is just wilted, stir in the cream mixture and remove from the heat.
Arrange a quarter of the of celery root slices, overlapping slightly, across the bottom of the prepared baking dish. Ladle 1/2 cup of the spinach, leek, and cream mixture over the celery root and spread evenly. Sprinkle 1/4 of the Gruyere cheese over the spinach. Repeat the layers 3 more times to fill the dish.
Cover loosely with foil and bake for 45 minutes, then remove the foil and bake for 45 minutes more until the gratin is golden brown and bubbling, and the celery root is tender when pierced with a paring knife.
Let the gratin rest at room temperature for 15 minutes before serving.
Thanksgiving Make-Ahead Note:
The gratin can be made and par-baked 2 days in advance. Bake, covered, for the initial 45 minutes, then cool to room temperature and cover tightly with foil or plastic wrap and refrigerate. On Thanksgiving Day, bring to room temperature before returning to the oven to bake uncovered for the final 45 minutes.