Vegan Potato Gratin

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Vegan Potato Gratin

Yield 12 servings

Craving comfort food as the weather cools down? Try this melt-in-your-mouth casserole, made with both sweet potatoes and russets in a creamy sauce. The cashews blend into a plant-based sauce that thickens as it bakes, creating a satisfying bite of nostalgia.

Ingredients

  • 1 cup raw cashews
  • 1 cup unsweetened oat milk
  • ½ cup vegetable stock
  • 1 Tablespoon white miso
  • 3 Tablespoons nutritional yeast
  • 2 teaspoons Dijon mustard
  • 1 teaspoon salt
  • 2 Tablespoons vegan butter, plus more for pan
  • 1 large yellow onion, thinly sliced
  • 2 cloves garlic, chopped
  • 2 Tablespoons fresh thyme, coarsely chopped, plus more for garnish
  • 2 pounds sweet potatoes, 2-inches wide, peeled and sliced
  • 2 pounds small russet potatoes, 2-inches wide, peeled and sliced
  • ½ cup vegan cheddar shreds, optional

Instructions

Cover the cashews with cold water and soak for at least 2 hours or overnight in the refrigerator. Drain and place in a blender and add the oat milk, vegetable stock, miso, nutritional yeast, Dijon mustard, and salt. Blend, scraping down the sides and repeating as necessary until very smooth, then set aside.

Preheat the oven to 400°. Use a slice of vegan butter to grease a 9x13 casserole. Melt 2 Tablespoons vegan butter in a medium sauté pan over medium heat, then add the onions. Sauté, stirring frequently, until soft and clear. Add garlic and thyme leaves, stir for a minute, remove from heat and set aside.

Using a mandolin, or by hand, slice the sweet potatoes into ⅛-inch thick rounds. Move to a bowl. Do the same for the russet potatoes and reserve them on the cutting board.

Arrange a row of sweet potato slices, standing up and shingled, along one long edge of the pan. Arrange a row of russet potato slices alongside it in the same way. Repeat to make four rows, alternating potatoes. Sprinkle with the onion mixture.

Drizzle the cashew sauce evenly over the rows of potato slices, and give the pan a gentle shake to make sure the sauce reaches the bottom. Cover the pan with foil and bake on the bottom rack for 45 minutes. Test the potatoes for doneness by piercing with a paring knife. If they’re not tender, re-cover and bake for an additional 10 minutes.

Uncover, move to the top rack and bake for 15 minutes, then take out and sprinkle with the vegan cheddar shreds if using. Return to the oven for 2 minutes to melt the shreds. Sprinkle with extra thyme if desired.

Let cool for 5 minutes before cutting.