Preheat the oven to 175 °C and prepare a baking dish.
Wash the sweet potatoes and pat them dry. Cut them in half lengthwise, and also cut a pi small piece from the rounded side to create a flat surface, ensuring the potatoes stay stable.
Roast the potatoes in the oven for 15 minutes beforehand.
Cut slices of brie and place them on the potatoes, and top with crumbled walnuts. Add salt and pepper to taste.
Return the potatoes to the oven and bake for an additional 8 minutes, allowing the brie to melt slightly.