Does a gratin have to have cheese? I don’t know but you certainly won’t miss it in this flavorful and seasonal potato and apple version.
I see no reason to peel the potatoes or apples, but you may if you prefer.
- 6 tablespoon unsalted butter, at room temperature, divided
- 1 pound red onions, peeled, halved & sliced
- 1 tablespoon chopped fresh rosemary leaves
- 3 teaspoon kosher salt, divided
- ⅓ cup water
- ⅓ cup dry white wine
- 1½ pound klondike rose, or similar idaho potatoes, sliced into ¼‑inch rounds
- 1 pound tart red apples (such as granny smith, pippin, or pink lady), peeled, halved, cored, cut into ¼‑inch-thick slices
- ¼ cup dried breadcrumbs
- ½ teaspoon freshly cracked black pepper
Preheat oven to 400 degrees F.
Melt 3 tablespoons butter in large nonstick skillet over medium heat. Add onions, rosemary, and 2 teaspoons salt; sauté until onions are tender and begin to carmelize, about 20 minutes. Pour in water and wine to deglaze the pan. Let the liquid come to a boil. Remove from heat, let cool about 5 minutes.
Place the potatoes, apples, remaining 1 teaspoon salt, pepper and cooled onion mixture in a large bowl; toss gently to combine. Transfer to 13 x 9 x 2‑inch baking dish, spreading evenly. Cover dish with parchment paper, then cover with foil, shiny side down. Bake gratin until potatoes are tender, about 45 minutes.
Remove from oven, uncover and dollop the remaining butter on top of the gratin. Sprinkle with breadcrumbs. Bake until top browns and juices bubble thickly, about 20 minutes longer. Can be made 6 hours ahead. Let stand uncovered at room temperature. Rewarm, loosely covered with foil, in 300 degree F oven for 20 minutes. Let gratin stand 15 minutes before serving.