Sweet Potato Gratin with Vanilla Bean and Bay Leaves
Heavy cream simmered with vanilla bean and bay leaves hints at marshmallow but is far more nuanced, compelling and aromatic. OR This no-marshmallow potato casserole retains a hint of marshmallow, but far more nuanced and aromatic, by infusing cream with vanilla.
- Makes8 servings
- Cook Time3 hours
- Active time plus cooling50 min active
- 1
For many families, Thanksgiving isn’t complete without a sweet potato casserole, that sticky-sweet concoction more appropriate for the dessert table than the main event. It’s a classic for good reason, though we felt the gooey marshmallows had to go. We started by roasting the sweet potatoes, a simple, hands-off process that can be done a day ahead. Roasting rather than boiling produces cleaner, deeper flavors and a better, less watery texture. In lieu of marshmallows we infuse cream with vanilla bean and bay leaves and add a dusting of black pepper for an overall effect that hints at marshmallow but is far more nuanced, compelling and aromatic. A crunchy topping of dark brown and white sugar with a touch of cayenne keeps the dish adults table-appropriate. We found that using a mesh strainer to sift the sugar over the potatoes produced even browning and an attractive crust. But strainers with very fine mesh tended to clog. If yours does this, just sprinkle the sugar by hand, smoothing it into an even layer with your palm.
Don’t get distracted while the gratin is broiling; all broilers are different, and the difference between browned and burnt can be a matter of seconds.
Step 1
Heat the oven to 400ºF with one rack in the middle position and another 6 inches from the broiler.
Pierce the sweet potatoes with a fork and arrange on a rimmed baking sheet. Bake on the middle rack, turning once, until tender, 1 to 1½ hours. Let cool.
Increase oven to 425ºF.
Step 2
While the potatoes roast, in a medium saucepan, combine the cream and bay leaves.
With a paring knife split the vanilla bean lengthwise, then scrape out the seeds. Add the seeds and pod to the cream and simmer over medium-high.
Set aside, covered, for 30 minutes. Strain out and discard the solids.
Step 3
Once cooled, peel the sweet potatoes and discard the skins. In a food processor, combine half the flesh and half the cream. Add 1 tablespoon of the brown sugar, the 3/4 teaspoon each salt and pepper. Process until smooth, about 1 minute, scraping the bowl halfway through; transfer to a large bowl.
Repeat with the remaining potatoes and cream, then add to the first batch. Mix well, then transfer to a 13-by-9-inch baking dish. Smooth the top.
Step 4
In a bowl, stir together the remaining brown sugar, the white sugar and the cayenne, if using.
Transfer to a medium mesh strainer, then sift the mixture over the surface of the potatoes to create an even sprinkling. Brush any sugar off the rim of the baking dish.
Step 5
Bake on the middle rack until bubbling at the edges, about 20 minutes.
Remove from the oven, then heat the broiler.
When ready, place the dish on the upper rack and broil until deeply browned and crisp, 2 to 7 minutes. Let sit for 20 minutes before serving.
