Mediterranean Layered Beet, Sweet Potato & Feta Gratin with Walnuts

Mediterranean Layered Beet, Sweet Potato & Feta Gratin with Walnuts

This Mediterranean Layered Beet, Sweet Potato & Feta Gratin with Walnuts is a colorful, comforting side dish that combines earthy roasted beets, naturally sweet sweet potatoes, tangy feta, crunchy walnuts, and fragrant herbs. Everything bakes together until tender, golden, and beautifully caramelized.

It’s elegant enough for a holiday table but simple enough for a cozy weekend dinner.

Ingredients

For the vegetables

• 3 medium sweet potatoes, peeled and thinly sliced
• 3 medium beets, peeled and thinly sliced
• 2 tablespoons olive oil
• 3 cloves garlic, finely minced
• 1 teaspoon dried oregano
• ½ teaspoon dried thyme
• ½ teaspoon smoked paprika
• ½ teaspoon salt
• ½ teaspoon freshly ground black pepper

For the creamy mixture

• ¾ cup (180 ml) heavy cream
• ½ cup (120 ml) whole milk
• 1 teaspoon Dijon mustard
• ½ teaspoon garlic powder
• ¼ teaspoon salt
• ¼ teaspoon black pepper

For layering

• 1½ cups (150 g) crumbled feta cheese
• ¾ cup (85 g) walnuts, roughly chopped
• ½ cup (50 g) grated Parmesan, optional
• 2 tablespoons chopped fresh parsley
• 1 tablespoon chopped fresh dill, optional

For finishing

• 1 tablespoon olive oil
• Fresh parsley
• Extra crumbled feta
• Lemon zest, optional
• A drizzle of honey, optional

Instructions

1. Preheat the oven.
   Heat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with olive oil.
2. Prepare the vegetables.
   Peel the sweet potatoes and beets. Slice both into very thin, even slices—about ⅛ inch (3 mm) thick.

   A mandoline makes this much easier, but a sharp knife works too. Try to keep the slices approximately the same thickness so everything cooks evenly.

3. Season the vegetables.
   Place the sweet potato slices in one bowl and the beet slices in another.

   Divide the olive oil, garlic, oregano, thyme, paprika, salt, and black pepper between the bowls. Toss each vegetable until evenly coated.

4. Prepare the cream mixture.
   In a small bowl, whisk together the heavy cream, milk, Dijon mustard, garlic powder, salt, and black pepper.
5. Begin layering.
   Arrange a layer of sweet potato slices across the bottom of the prepared baking dish.
6. Add beets and feta.
   Add a layer of beet slices, followed by a small handful of crumbled feta and chopped walnuts.
7. Continue layering.
   Repeat the layers, alternating sweet potatoes and beets and sprinkling feta and walnuts between the layers.

   Reserve some feta and walnuts for the top.

8. Add the cream mixture.
   Slowly pour the cream mixture over the layered vegetables, allowing it to work its way down between the slices.

   Don’t pour it all in one place—distribute it evenly across the dish.

9. Add the final toppings.
   Sprinkle the Parmesan, remaining feta, and walnuts over the top. Finish with a light drizzle of olive oil.
10. Cover and bake.
    Cover the dish tightly with aluminum foil and bake for 45–55 minutes.
11. Uncover and continue baking.
    Remove the foil and continue baking for another 20–30 minutes, until the vegetables are completely tender and the top is golden brown.

    If you want a deeper golden crust, place the gratin under the broiler for 1–2 minutes at the end, watching carefully.

12. Rest before serving.
    Let the gratin rest for 10–15 minutes before cutting. This gives the creamy sauce time to settle and makes the layers easier to serve.
13. Garnish.
    Sprinkle with fresh parsley and dill. Add extra feta and a little lemon zest for a fresh Mediterranean finish.

Tips for the Best Gratin

• Slice the vegetables thinly and evenly. Thick slices take longer to cook and can make the gratin uneven.
• Don’t skip the covered baking stage. It traps steam and helps the beets and sweet potatoes become tender.
• Remove the foil toward the end so the top can brown and become slightly crisp.
• If your beets are particularly large, cut the slices into smaller half-moons so they layer more easily.
• Let the gratin rest before serving so it doesn’t fall apart when sliced.
• Toast the walnuts beforehand for an even richer, nuttier flavor.

Mediterranean Flavor Boost

For an even more Mediterranean-style dish, add:

• ½ cup chopped Kalamata olives
• 1 teaspoon lemon zest
• ½ teaspoon crushed red pepper flakes
• 2 tablespoons fresh oregano
• A drizzle of extra-virgin olive oil after baking

You can also add a little crumbled goat cheese alongside the feta for a richer flavor.

Honey-Walnut Finish

The combination of earthy beets, salty feta, and sweet potatoes is especially good with a tiny amount of honey.

After baking, drizzle 1–2 teaspoons of honey over the top and sprinkle with toasted walnuts and fresh herbs. The sweet-salty contrast is delicious.

Make-Ahead Instructions

You can assemble the gratin several hours ahead of time. Cover it tightly and refrigerate until ready to bake.

Take it out of the refrigerator while the oven preheats, then bake as directed. Because the vegetables will be cold, you may need to add 10–15 minutes to the covered baking time.

Storage

Store leftovers in an airtight container in the refrigerator for up to 4 days.

Reheat individual portions in the microwave or warm the entire dish in a 350°F (175°C) oven until heated through.

Makes

8 servings as a side dish

Serve it alongside roasted chicken, grilled fish, lamb, or a simple Mediterranean salad. The combination of creamy sweet potatoes, earthy beets, tangy feta, and crunchy walnuts makes this gratin hearty enough to be the centerpiece of a vegetarian meal as well.