Crispy Sweet Potato & Butternut Rosti Tart with Feta, Spinach, Cranberry & Sage Brown Butter + Walnut Honey is a beautiful savoury tart that combines a golden, crispy vegetable crust with a creamy, flavour-packed filling. Sweet potato and butternut squash form the base, while spinach, tangy feta, and sweet dried cranberries bring colour, texture, and a delicious balance of flavours.

The finishing touches make this tart especially memorable. Nutty sage brown butter adds a rich, aromatic flavour, while honey-coated walnuts provide a delicate sweetness and satisfying crunch. Perfect for an autumn lunch, a vegetarian dinner, or a special gathering, this tart looks impressive on the table while using simple, familiar ingredients.

Ingredients

For the Sweet Potato and Butternut Rosti Crust:

2 cups sweet potatoes, peeled and coarsely grated (300 g)
2 cups butternut squash, peeled and coarsely grated (300 g)
2 large eggs (100 g)
¼ cup all-purpose flour (30 g)
½ cup grated Parmesan cheese (50 g)
1 tsp garlic powder (3 g)
½ tsp dried thyme (1 g)
½ tsp kosher salt (3 g)
¼ tsp black pepper (0.5 g)
2 tbsp olive oil (30 ml)

For the Spinach and Feta Filling:

3 cups fresh spinach, roughly chopped (90 g)
1 cup crumbled feta cheese (150 g)
⅓ cup dried cranberries (50 g)
1 small onion, finely chopped (80 g)
2 cloves garlic, minced (6 g)
1 tbsp olive oil (15 ml)
¼ tsp black pepper (0.5 g)

For the Sage Brown Butter:

4 tbsp unsalted butter (56 g)
8 fresh sage leaves (4 g)
1 tsp fresh lemon juice (5 ml)

For the Walnut Honey:

¾ cup walnuts, roughly chopped (85 g)
2 tbsp honey (42 g)
1 tsp unsalted butter (5 g)
¼ tsp ground cinnamon (0.5 g)
Pinch of kosher salt

How to Make It

1. Prepare the Oven and Tart Pan

Preheat the oven to 400°F (200°C). Grease a 9-inch (23 cm) tart pan or round baking dish with olive oil, making sure the base and sides are lightly coated to help prevent sticking.

2. Prepare the Rosti Mixture

Place the grated sweet potatoes and butternut squash in a clean kitchen towel. Squeeze firmly to remove as much excess moisture as possible. This step helps the crust become crisp rather than soft.

Transfer the vegetables to a large bowl. Add the eggs, flour, Parmesan, garlic powder, dried thyme, salt, and black pepper. Mix thoroughly until the ingredients are evenly combined.

3. Shape and Bake the Crust

Press the rosti mixture firmly into the prepared tart pan, spreading it across the bottom and up the sides to form an even crust. Brush the surface lightly with olive oil.

Bake for 25–30 minutes, until the edges are golden and crisp and the base has begun to set. If the centre looks particularly moist, allow it a few extra minutes before adding the filling.

4. Cook the Onion and Garlic

While the crust bakes, heat 1 tablespoon of olive oil in a skillet over medium heat. Add the chopped onion and cook for 4–5 minutes, stirring occasionally, until softened.

Add the minced garlic and cook for another 30 seconds, stirring constantly so it becomes fragrant without burning.

5. Prepare the Spinach and Feta Filling

Add the chopped spinach to the skillet and cook for 2–3 minutes, until wilted. Remove the skillet from the heat and allow the mixture to cool slightly.

Drain any excess liquid to prevent the tart from becoming soggy. Fold in the crumbled feta, dried cranberries, and black pepper until evenly distributed.

6. Fill and Bake the Tart

Spread the spinach and feta mixture evenly over the pre-baked rosti crust. Return the tart to the oven and bake for another 10–15 minutes, until the filling is heated through and the top is lightly golden.

Remove the tart from the oven and set it aside while you prepare the finishing toppings.

7. Make the Walnut Honey

Place the chopped walnuts, honey, butter, cinnamon, and a pinch of salt in a small nonstick skillet over medium-low heat.

Cook for 3–5 minutes, stirring frequently, until the walnuts are glossy and coated in the honey mixture. Transfer them to parchment paper and allow them to cool slightly. They will become firmer as they cool, adding a lovely crunch to the finished tart.

8. Prepare the Sage Brown Butter

Melt the butter in a small saucepan over medium-low heat. Add the fresh sage leaves and cook for 3–5 minutes, swirling the pan occasionally, until the butter turns golden brown and develops a nutty aroma.

Watch carefully toward the end, as butter can brown quickly. Remove the saucepan from the heat and stir in the fresh lemon juice.

9. Finish and Serve

Let the tart rest for 5–10 minutes before slicing. Drizzle the sage brown butter over the top and scatter the honey-coated walnuts evenly across the filling.

Serve warm while the rosti crust retains its crisp edges and the spinach and feta filling remains creamy.

Why This Recipe Works

The grated sweet potato and butternut squash create a naturally colourful crust with a slightly sweet flavour and crisp edges. Removing excess moisture before mixing is essential for achieving a firm base that holds together when sliced. Eggs, flour, and Parmesan help bind the vegetables, while garlic and thyme add savoury depth.

The filling balances the sweetness of the crust with salty feta, tender spinach, and tart cranberries. The finishing toppings bring everything together: sage brown butter adds richness and a nutty aroma, while honey-coated walnuts provide sweetness and crunch. A little lemon juice brightens the butter and helps balance the richness of the cheese and nuts.

Crispy Sweet Potato & Butternut Rosti Tart with Feta, Spinach, Cranberry & Sage Brown Butter + Walnut Honey

Tips for the Best Sweet Potato and Butternut Rosti Tart

Remove as much moisture as possible: Squeeze the grated vegetables thoroughly in a clean kitchen towel to help the crust crisp and hold its shape.
Press the crust firmly: Compact the mixture evenly across the base and sides of the tart pan to reduce crumbling when slicing.
Pre-bake the crust: Give the vegetable base its full initial baking time before adding the filling.
Drain the spinach well: Excess liquid can make the crust soft, so remove as much moisture as possible before mixing in the feta.
Keep the walnut mixture moving: Stir frequently over medium-low heat to prevent the honey from scorching.
Watch the brown butter carefully: Remove it from the heat as soon as it turns golden brown and smells nutty, as it can quickly become burnt.
Allow the tart to rest: Resting for 5–10 minutes helps the filling settle and makes cleaner slices easier to achieve.
Add the toppings just before serving: The brown butter and walnut honey are best added at the end to preserve their aroma and texture.

Serving Suggestions

Serve this tart as a vegetarian main course with a fresh green salad dressed in lemon vinaigrette. The bright, tangy dressing complements the creamy feta, sweet root vegetables, and rich brown butter without overpowering them.

For a more substantial meal, pair it with roasted Brussels sprouts, green beans, or a simple vegetable soup. It also makes an attractive centrepiece for an autumn lunch or dinner gathering. Cut it into wedges and finish each slice with a little extra walnut honey for a lovely balance of savoury, sweet, and nutty flavours.

Frequently Asked Questions

Can I prepare the tart ahead of time?

Yes. You can bake the rosti crust and prepare the spinach and feta filling in advance. Store them separately in the refrigerator, then assemble and bake the tart before serving. Prepare the walnut honey and sage brown butter close to serving time for the best flavour and texture.

How do I keep the rosti crust crispy?

The most important step is removing excess moisture from the grated vegetables. Press the mixture firmly into the pan and bake the crust until golden before adding the filling. Make sure the cooked spinach is well drained, too.

Can I use frozen spinach?

Yes. Thaw it completely and squeeze out as much water as possible before adding it to the cooked onion and garlic. Frozen spinach may release more moisture than fresh spinach, so draining it thoroughly is particularly important.

Can I substitute another cheese for feta?

Yes. Goat cheese provides a creamy texture and tangy flavour, while ricotta offers a milder result. If using ricotta, drain it well to avoid adding excess moisture to the filling.

Can I make this tart without walnuts?

Yes. You can omit the walnuts or replace them with pecans for a similar sweet, nutty finish. If you need a nut-free version, leave them out and drizzle the tart with the sage brown butter and honey instead.

How should I store leftovers?

Allow the tart to cool, then transfer it to an airtight container and refrigerate for up to 3 days. For the best texture, store any remaining walnut honey separately when possible.

What is the best way to reheat the tart?

Reheat individual slices in an oven at 180°C (350°F) until warmed through. An oven or air fryer helps restore some crispness to the crust. Add a little fresh sage brown butter or walnut honey after reheating if desired.

Can I make the tart gluten-free?

Yes. Replace the all-purpose flour with a suitable gluten-free plain flour blend. Check the labels on the Parmesan and other packaged ingredients if you need to avoid gluten completely.

Nutrition & Timing

Details	Amount
Servings	6
Prep Time	25 minutes
Cook Time	45 minutes
Resting Time	5–10 minutes
Total Time	Approximately 1 hour 15 minutes
Calories	390
Protein	12 g
Carbohydrates	38 g
Fat	23 g
Fiber	5 g
Sugar	14 g
Sodium	570 mg

Nutritional values are approximate and may vary depending on the specific ingredients and brands used.

Final Thoughts

Crispy Sweet Potato & Butternut Rosti Tart with Feta, Spinach, Cranberry & Sage Brown Butter + Walnut Honey is a delicious way to turn everyday vegetables into a special meal. The crisp, golden crust, creamy savoury filling, and sweet, nutty toppings create a wonderful contrast in every bite.

Serve it warm for lunch, dinner, or a seasonal gathering, and let the sage brown butter and honey-coated walnuts provide the finishing touch. With its colourful layers and balanced flavours, this tart is a lovely addition to any collection of comforting vegetarian recipes.