Sweet Potato & Apple Gratin with Brie, Cranberries & Walnut Crumble
Sweet Potato & Apple Gratin with Brie, Cranberries & Walnut Crumble is a comforting, beautifully layered side dish that brings together tender sweet potatoes, lightly sweet apples, creamy Brie, tart dried cranberries, and crunchy walnuts. The combination of sweet, savoury, creamy, and nutty flavours makes every bite wonderfully balanced.
Finished with a golden walnut crumble and fresh thyme, this gratin is an elegant choice for holiday dinners, family gatherings, or any meal where you want a warm and impressive vegetable side. The creamy Brie sauce settles between the layers as the sweet potatoes and apples become tender in the oven.
Ingredients
For the Sweet Potato & Apple Layers:
- 3 medium sweet potatoes, peeled and thinly sliced (750 g)
- 3 medium apples, peeled, cored, and thinly sliced (450 g)
- 2 tbsp unsalted butter, melted (28 g)
- 1 tbsp pure maple syrup (20 g)
- 1 tsp fresh thyme leaves (2 g)
- ½ tsp ground cinnamon (1.5 g)
- ½ tsp salt (3 g)
- ¼ tsp black pepper (0.5 g)
For the Creamy Brie Sauce:
- 6 oz Brie cheese, rind removed and chopped (170 g)
- 1 cup heavy cream (240 ml)
- ½ cup whole milk (120 ml)
- 1 clove garlic, minced (3 g)
- ¼ tsp ground nutmeg (0.5 g)
- ¼ tsp salt (1.5 g)
For the Walnut Crumble:
- ¾ cup walnuts, roughly chopped (85 g)
- ½ cup panko breadcrumbs (30 g)
- 2 tbsp all-purpose flour (16 g)
- 2 tbsp unsalted butter, melted (28 g)
- 2 tbsp dried cranberries, finely chopped (20 g)
- 1 tbsp fresh thyme leaves (3 g)
For the Topping:
- ⅓ cup dried cranberries (50 g)
- 1 tbsp fresh thyme leaves (3 g)
How to Make It
1. Prepare the Oven and Baking Dish
Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch (23×33 cm) baking dish to prevent the gratin from sticking and make serving easier.
2. Layer the Sweet Potatoes and Apples
Arrange alternating layers of thinly sliced sweet potatoes and apples in the prepared baking dish, slightly overlapping each slice. Drizzle the layers evenly with melted butter and maple syrup, then sprinkle with fresh thyme, cinnamon, salt, and black pepper.
3. Make the Brie Sauce
Combine the heavy cream, whole milk, minced garlic, nutmeg, and salt in a small saucepan over medium-low heat. Warm gently without allowing the mixture to boil. Add the chopped Brie and stir until the cheese has melted into a smooth, creamy sauce.
4. Add the Brie Sauce
Pour the warm Brie sauce evenly over the sweet potato and apple layers. Gently spread it across the surface if needed, allowing the creamy sauce to settle into the spaces between the slices.
5. Prepare the Walnut Crumble
In a bowl, combine the chopped walnuts, panko breadcrumbs, flour, melted butter, finely chopped dried cranberries, and fresh thyme. Stir until everything is evenly coated and the mixture forms a coarse, crumbly topping.
6. Assemble the Topping
Scatter the walnut crumble evenly over the gratin. Sprinkle the remaining dried cranberries over the top so they become lightly toasted and add pops of sweet-tart flavour as the gratin bakes.
7. Bake the Gratin
Cover the baking dish loosely with foil and bake for 40 minutes. Remove the foil and continue baking for another 20–25 minutes, or until the sweet potatoes are tender and the walnut topping is golden and crisp.
8. Rest and Serve
Let the gratin rest for 10–15 minutes before serving. Finish with fresh thyme and serve warm while the Brie sauce is creamy and the walnut crumble remains crunchy.
Why This Recipe Works
This gratin works beautifully because the sweet potatoes and apples bring natural sweetness and contrasting textures, while the creamy Brie sauce adds richness and a savoury depth. Cinnamon, garlic, nutmeg, and fresh thyme complement the fruit and cheese without overpowering them.
The walnut crumble adds an important crunchy contrast to the soft, creamy layers underneath. Dried cranberries bring a bright tartness that balances the richness of the Brie and butter, while maple syrup ties the sweet and savoury flavours together.
Tips for the Best Sweet Potato & Apple Gratin
- Slice evenly: Cut the sweet potatoes and apples into thin, consistent slices so they cook evenly and create neat layers.
- Keep the sauce gentle: Warm the cream and milk without boiling before adding the Brie for a smooth, creamy sauce.
- Do not skip the foil: Covering the gratin during the first part of baking helps the sweet potatoes become tender before the crumble is browned.
- Watch the final bake: Once the foil is removed, keep an eye on the walnut topping so it becomes crisp and golden without over-browning.
- Let it rest: A 10–15 minute resting period allows the creamy sauce to settle and makes the gratin easier to serve.
Serving Suggestions
Serve this gratin warm alongside roasted chicken, turkey, pork, or another favourite main course. The combination of sweet potatoes, apples, Brie, cranberries, and walnuts makes it especially suited to autumn and holiday meals.
For a beautiful presentation, finish each serving with a little fresh thyme and a few extra toasted walnuts. Serve it directly from the baking dish while the centre is creamy and the topping is still crisp.
Frequently Asked Questions
What type of apples work best for this gratin?
Crisp apples with a balance of sweetness and tartness work well because they hold their shape during baking while complementing the sweet potatoes and creamy Brie sauce.
Can I prepare the gratin ahead of time?
You can prepare the sliced ingredients, Brie sauce, and walnut crumble ahead of time and keep them separately until ready to assemble and bake. For the best texture, add the crumble just before baking.
Can I use another cheese instead of Brie?
Brie provides the smooth, creamy texture intended for this recipe. If needed, another mild, soft cheese that melts well can be used, although the flavour and texture will be slightly different.
How do I keep the walnut crumble crisp?
Add the crumble to the gratin before baking and remove the foil for the final 20–25 minutes. This allows the topping to brown and crisp while the sweet potato and apple layers finish cooking.
Why should the gratin rest before serving?
Resting for 10–15 minutes gives the creamy Brie sauce time to settle between the layers and makes the gratin easier to portion without losing too much of the sauce.
Nutrition & Timing
| Details | Amount |
|---|---|
| Servings | 8 |
| Prep Time | 20 minutes |
| Cook Time | 60–65 minutes |
| Total Time | 80–85 minutes, plus 10–15 minutes resting |
| Calories | 465 |
| Protein | 11 g |
| Carbohydrates | 48 g |
| Fat | 27 g |
| Fiber | 7 g |
| Sugar | 23 g |
| Sodium | 390 mg |
Final Thoughts
Sweet Potato & Apple Gratin with Brie, Cranberries & Walnut Crumble brings together everything you want in a special side dish: tender layered vegetables and fruit, a rich creamy sauce, bright dried cranberries, and a golden crunchy topping.
It is comforting enough for a cosy family dinner yet elegant enough for a holiday table. Serve it warm with plenty of fresh thyme for a beautiful finishing touch and a delicious balance of creamy, sweet, savoury, tart, and crunchy textures.
Print
Sweet Potato & Apple Gratin with Brie, Cranberries & Walnut Crumble
- Total Time: 1 hour 25 minutes
Description
A comforting layered gratin featuring tender sweet potatoes and apples baked with a creamy Brie sauce, tart dried cranberries, and a golden walnut crumble. Fresh thyme brings everything together for an elegant side dish perfect for holiday dinners and family gatherings.
Ingredients
For the Sweet Potato & Apple Layers:
3 medium sweet potatoes, peeled and thinly sliced (750 g)
3 medium apples, peeled, cored, and thinly sliced (450 g)
2 tbsp unsalted butter, melted (28 g)
1 tbsp pure maple syrup (20 g)
1 tsp fresh thyme leaves (2 g)
½ tsp ground cinnamon (1.5 g)
½ tsp salt (3 g)
¼ tsp black pepper (0.5 g)
For the Creamy Brie Sauce:
6 oz Brie cheese, rind removed and chopped (170 g)
1 cup heavy cream (240 ml)
½ cup whole milk (120 ml)
1 clove garlic, minced (3 g)
¼ tsp ground nutmeg (0.5 g)
¼ tsp salt (1.5 g)
For the Walnut Crumble:
¾ cup walnuts, roughly chopped (85 g)
½ cup panko breadcrumbs (30 g)
2 tbsp all-purpose flour (16 g)
2 tbsp unsalted butter, melted (28 g)
2 tbsp dried cranberries, finely chopped (20 g)
1 tbsp fresh thyme leaves (3 g)
For the Topping:
⅓ cup dried cranberries (50 g)
1 tbsp fresh thyme leaves (3 g)
Instructions
1. Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch (23×33 cm) baking dish.
2. Arrange alternating layers of thinly sliced sweet potatoes and apples in the prepared baking dish, slightly overlapping each slice. Drizzle evenly with melted butter and maple syrup, then sprinkle with fresh thyme, cinnamon, salt, and black pepper.
3. Combine the heavy cream, whole milk, minced garlic, nutmeg, and salt in a small saucepan over medium-low heat. Warm gently without boiling. Add the chopped Brie and stir until melted into a smooth, creamy sauce.
4. Pour the warm Brie sauce evenly over the sweet potato and apple layers, allowing it to settle between the slices.
5. In a bowl, combine the chopped walnuts, panko breadcrumbs, flour, melted butter, finely chopped dried cranberries, and fresh thyme. Stir until evenly coated and crumbly.
6. Scatter the walnut crumble evenly over the gratin and sprinkle the remaining dried cranberries over the top.
7. Cover the baking dish loosely with foil and bake for 40 minutes. Remove the foil and continue baking for 20–25 minutes, or until the sweet potatoes are tender and the walnut topping is golden and crisp.
8. Let the gratin rest for 10–15 minutes before serving. Finish with fresh thyme and serve warm.
Notes
Slice the sweet potatoes and apples evenly so they cook at the same rate and create neat layers. Warm the cream and milk gently without boiling before adding the Brie for a smooth sauce. Covering the gratin during the first part of baking helps the sweet potatoes become tender before the crumble browns. Watch the final 20–25 minutes closely so the walnut topping becomes golden and crisp without over-browning. Let the gratin rest for 10–15 minutes before serving so the creamy Brie sauce can settle between the layers. Crisp apples with a balance of sweetness and tartness work well because they hold their shape during baking. Prepare the sliced ingredients, Brie sauce, and walnut crumble separately ahead of time, then assemble and bake when ready. For the best texture, add the walnut crumble just before baking. Another mild, soft cheese that melts well can be substituted for Brie, although the flavour and texture will be different. Serve warm alongside roasted chicken, turkey, pork, or another favourite main course. Finish with fresh thyme and a few extra toasted walnuts for presentation.
- Prep Time: 20 minutes
- Cook Time: 65 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: American
