Skinny Sweet Potato Gratin Recipe



  • 3 pounds sweet potatoes (about 4 medium), peeled and sliced 1/4-inch thick

Flavor base:

  • 1 tablespoon olive oil
  • 1/2 cup chopped onion
  • 1/4 teaspoon dried thyme (or 1 teaspoon fresh thyme)
  • 2 cloves garlic, minced

Dairy-free sauce:

  • 1 1/2 cups unsweetened almond milk
  • 1/4 cup nutritional yeast (optional, for cheesy flavor)
  • Salt and black pepper to taste

Topping (optional):

  • 1/4 cup gluten-free breadcrumbs (or regular breadcrumbs)
  • 1 tablespoon chopped fresh parsley
  • 1 tablespoon olive oil


  • Mandoline slicer (optional, for even slices)
  • 9×13 inch baking dish
  • Large skillet


Prep work:

  • Preheat oven to 400 degrees F (200 degrees C).
  • Grease your baking dish lightly with cooking spray.

Cook the flavor base:

  • In a large skillet, heat the olive oil over medium heat. Add the onions and cook until softened, about 5 minutes.
  • Add the thyme and garlic, cook for another minute until fragrant.

Make the sauce:

  • Slowly whisk in the almond milk to the skillet. Add nutritional yeast if using. Season generously with salt and pepper. Bring to a simmer and cook for a minute or two until slightly thickened. Then remove from heat.

Layer the gratin:

  • Layer half of the sweet potatoes in the prepared baking dish, overlapping slightly. Season lightly with salt and pepper.
  • Pour half of the sauce mixture over the potato layer.
  • Repeat with the remaining sweet potatoes and sauce.

Optional topping:

  • In a small bowl, combine the breadcrumbs, parsley, and olive oil. Sprinkle the breadcrumb mixture evenly over the top of the sweet potato gratin.


  • Cover the dish with foil and bake for 30 minutes.
  • Remove foil and bake for an additional 20-25 minutes, or until the potatoes are tender and the top is golden brown.

Rest and serve:

  • Let the gratin rest for 5-10 minutes before serving. This allows the sauce to thicken slightly.


  • Customize it: Swap out half the sweet potatoes for regular potatoes for a different flavor profile.
  • Make it cheesy: Add some grated Parmesan cheese to the sauce or topping if you prefer a richer dish.
  • Mandoline = Even slices: A mandoline slicer helps to create evenly thin potato slices for more consistent cooking.
  • Storage: The gratin will keep in the fridge for 3-4 days. Reheat gently in the oven or microwave.


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