A cozy Mediterranean-inspired bake combining golden roasted sweet potatoes, garlicky spinach, caramelized onion, tangy feta, and crunchy toasted walnuts. The sweet and savory combination is especially delicious with a little lemon and fresh herbs. Similar versions pair roasted sweet potatoes with spinach, feta, walnuts, and caramelized onions for a hearty vegetarian bake.
Ingredients
For the Roasted Sweet Potatoes
3 large sweet potatoes, peeled and cut into ¾-inch cubes
2 tbsp extra-virgin olive oil
1 tsp dried oregano
½ tsp smoked paprika
½ tsp garlic powder
½ tsp salt
¼ tsp black pepper
For the Caramelized Onion
2 large yellow onions, thinly sliced
1 tbsp olive oil
1 tbsp butter, optional
¼ tsp salt
1 tsp balsamic vinegar
½ tsp dried thyme
For the Spinach
8 oz (225 g) fresh baby spinach
2 garlic cloves, minced
1 tsp olive oil
Pinch of salt
¼ tsp black pepper
½ tsp lemon zest
For the Topping
¾ cup crumbled feta cheese
½ cup walnuts, roughly chopped
2 tbsp fresh parsley, chopped
1 tbsp fresh thyme
Pinch of red pepper flakes, optional
Optional Lemon Finish
1 tbsp fresh lemon juice
1 tsp extra-virgin olive oil
Instructions
- Roast the Sweet Potatoes
Preheat the oven to 425°F (220°C).
Line a large baking sheet with parchment paper.
Add the cubed sweet potatoes to a large bowl. Toss with olive oil, oregano, smoked paprika, garlic powder, salt, and black pepper.
Spread the potatoes in a single layer, leaving space between the pieces.
Roast for 25–30 minutes, turning once halfway through, until tender and golden around the edges.
Tip: Don’t overcrowd the pan. Space around the sweet potatoes helps them roast instead of steam.
- Caramelize the Onions
While the sweet potatoes roast, heat olive oil and optional butter in a large skillet over medium-low heat.
Add sliced onions and ¼ teaspoon salt.
Cook for 20–25 minutes, stirring every few minutes, until soft, golden, and caramelized.
Stir in balsamic vinegar and thyme during the final 1–2 minutes.
Remove from the heat.
- Cook the Spinach
Heat 1 teaspoon olive oil in another skillet over medium heat.
Add minced garlic and cook for about 30 seconds.
Add spinach in handfuls.
Cook for 2–3 minutes, stirring, until just wilted.
Season with black pepper, a small pinch of salt, and lemon zest.
If the spinach releases excess liquid, drain it well. Removing excess moisture helps prevent a watery bake.
- Prepare the Walnuts
For extra flavor, place the chopped walnuts in a dry skillet over medium-low heat.
Toast for 2–4 minutes, stirring frequently, until fragrant.
Remove immediately from the heat so they don’t burn.
- Assemble the Bake
Reduce the oven to 375°F (190°C).
Lightly grease a 9×13-inch baking dish.
Add the roasted sweet potatoes.
Spread the caramelized onions over the top.
Add the wilted spinach.
Sprinkle with about ½ cup feta and half of the toasted walnuts.
Gently toss or layer the ingredients without crushing the sweet potatoes.
- Add the Topping
Sprinkle the remaining feta and walnuts evenly over the top.
Add fresh parsley, thyme, and red pepper flakes if using.
- Bake
Bake uncovered at 375°F (190°C) for 15–20 minutes, until:
The bake is heated through
The feta is softened and lightly golden
The walnuts are fragrant and toasted
Watch the walnuts during the last few minutes because they can brown quickly.
- Finish
Remove from the oven and let the bake rest for 5 minutes.
Drizzle with fresh lemon juice and a little extra olive oil.
Garnish with fresh parsley and thyme.
Serve warm.
Recipe Details
Prep Time: 20 minutes
Roasting Time: 25–30 minutes
Assembly/Baking: 15–20 minutes
Onion Cooking: 20–25 minutes
Total Time: About 1 hour 10 minutes
Servings: 6
Course: Main Dish / Side Dish
Cuisine: Mediterranean-inspired
Diet: Vegetarian
Difficulty: Easy to Moderate
Approximate Nutrition
Per serving:
Calories: 350–400
Protein: 8–10g
Carbohydrates: 42–48g
Fat: 18–22g
Fiber: 7–9g
Sugar: 10–13g
Nutrition is approximate and depends on the amount of feta, walnuts, olive oil, and sweet potato used.
Nut & Allergen Information
Tree Nuts
Yes — walnuts are included.
Walnuts are a tree nut and should be clearly identified for anyone with a tree-nut allergy.
Peanuts
None in the recipe.
Dairy
Yes: feta cheese
Optional butter also contains dairy.
Eggs
None
Wheat/Gluten
Naturally gluten-free as written.
Soy
None intentionally added
Sesame
None
Nut-Free Version
To make this recipe completely nut-free, omit the walnuts. For crunch, use toasted pumpkin seeds or sunflower seeds only if those are safe for the intended person.
Dairy-Free Version
Replace feta with a dairy-free feta alternative or omit it. Use olive oil instead of butter.
Vegan Version
Use dairy-free feta and olive oil instead of butter.
Easy Substitutions
Sweet potatoes:
Use butternut squash or pumpkin cubes.
Spinach:
Use kale, Swiss chard, or baby spinach.
Walnuts:
Use pecans, almonds, pistachios, or pine nuts—but these are also tree nuts. For a nut-free version, use pumpkin or sunflower seeds.
Feta:
Use goat cheese, crumbled ricotta salata, or dairy-free feta.
Yellow onion:
Red onion or shallots work well.
Fresh herbs:
Use parsley, dill, basil, rosemary, or thyme.
Balsamic vinegar:
Use red wine vinegar for a sharper flavor.
Helpful Tips
Cut the sweet potatoes into similar-sized pieces so they cook evenly.
Roast the sweet potatoes separately before assembling. This gives them caramelized edges and deeper flavor.
Cook the onions slowly rather than using high heat.
Squeeze or drain cooked spinach well before adding it to the casserole.
Toast the walnuts separately for the best crunch.
Add lemon juice after baking to brighten the flavors.
For a stronger Mediterranean flavor, add a little za’atar or extra oregano.
If you want a sweeter finish, drizzle a very small amount of honey over individual servings.
How to Add More Protein
For a more substantial main course, add:
1½ cups cooked chickpeas
1 cup cooked white beans
Grilled chicken
Grilled salmon
Cooked lentils
Extra feta
Chickpeas are particularly good with the sweet potato, spinach, feta, and Mediterranean herbs.
What to Serve With It
This bake works beautifully with:
Greek salad
Cucumber tomato salad
Lemon-herb chicken
Grilled salmon
Roasted vegetables
Lentil salad
Hummus and pita
Quinoa
Tzatziki
It can also be served as a vegetarian main dish with a simple green salad.
Storage & Reheating
Refrigerator
Store leftovers in an airtight container for 3–4 days.
Reheating
Reheat in a 350°F (175°C) oven for 10–15 minutes, or microwave individual portions until heated through.
For the best texture, add a few fresh walnuts after reheating.
Freezing
The bake can be frozen, but the spinach and feta may soften slightly after thawing. For best quality, freeze portions for up to 2 months.
Thaw overnight in the refrigerator and reheat until hot.
Q&A
Q: Can I use frozen spinach?
Yes. Thaw it completely and squeeze out as much water as possible before adding it to the bake.
Q: Can I make this without walnuts?
Absolutely. Simply omit them or replace them with pumpkin or sunflower seeds for crunch.
Q: Are walnuts considered tree nuts?
Yes. Walnuts are classified as tree nuts, so this recipe is not tree-nut-free as written.
Q: Can I use pecans instead of walnuts?
Yes, but pecans are also tree nuts.
Q: Can I make this dairy-free?
Yes. Omit the feta or use a dairy-free feta alternative, and replace butter with olive oil.
Q: Can I make it vegan?
Yes. Use dairy-free feta and olive oil.
Q: Can I make this gluten-free?
Yes. The recipe is naturally gluten-free; just check packaged ingredients such as seasonings and dairy alternatives if necessary.
Q: Can I add chickpeas?
Yes. Add about 1–1½ cups cooked chickpeas during assembly. They make the bake more filling and add plant-based protein.
Q: Can I use butternut squash instead of sweet potato?
Yes. Cut the squash into similar-sized cubes and roast until tender and caramelized.
Q: Why are my sweet potatoes mushy?
Usually because the pieces were overcrowded on the baking sheet or cut too small. Spread them out in a single layer and roast at high heat.
Q: How can I make the walnuts extra crunchy?
Toast them separately in a dry skillet for a few minutes and add some immediately after baking rather than exposing all of them to the oven heat.
Q: Can I prepare this ahead of time?
Yes. Roast the sweet potatoes, caramelize the onions, and cook the spinach up to a day ahead. Refrigerate separately, then assemble and bake when ready.
Q: Can I add garlic?
Yes. Garlic works particularly well with the spinach. You can also add roasted garlic to the sweet potatoes.
Q: Can I make it spicy?
Yes. Add red pepper flakes, Aleppo pepper, or a pinch of cayenne.
Q: Can I use goat cheese instead of feta?
Yes. Goat cheese gives the bake a softer, creamier and slightly tangy flavor.
Q: Is this suitable as a meal-prep recipe?
Yes. Portion it into containers and refrigerate for up to 3–4 days. Reheat gently and add fresh herbs and walnuts afterward for better texture.
Q: What is the best finishing touch?
A squeeze of fresh lemon juice, a drizzle of extra-virgin olive oil, fresh parsley, and a few freshly toasted walnuts bring the whole dish together.
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