Sweet Potato, Apple & Onion Gratin

This sweet potato gratin layers thinly sliced sweet potatoes with tart Granny Smith apples and sauteed onions, then tops everything with a crunchy crust of breadcrumbs, sharp cheddar, and crumbled bacon. It’s a Thanksgiving side dish that steals the show from the turkey.

The tart apples are essential to the balance here. They cut through the sweetness of the potatoes and the richness of the bacon-cheddar topping. Tossing the apple slices in flour before layering helps thicken the chicken stock as it bakes, creating a silky sauce between the layers.

Three stages of cooking build the texture: 45 minutes covered lets the sweet potatoes cook through and the stock reduces, 20 minutes with the breadcrumb topping sets the crust, and a final broil turns everything golden and crunchy on top.

Chef Tips

• Slice the sweet potatoes a uniform ¼ inch thick. Uneven slices mean some are mushy while others are still crunchy.
• Saute the onions the full 10 minutes until genuinely tender. Undercooked onions stay sharp and don’t meld into the gratin properly.
• Use fresh breadcrumbs, not the dried kind from a can. Fresh crumbs crisp up under the broiler while dried crumbs just burn.
• Watch the broiler closely during the final step. The cheese and breadcrumbs go from golden to charred in seconds.

Variations

• Use Honeycrisp or Braeburn apples instead of Granny Smith if you want a sweeter gratin.
• Add a layer of fresh sage leaves between the potato and apple layers for an herbal note.
• Skip the bacon for a vegetarian version and use vegetable broth in place of chicken.