Ingredients:

  • 4 kg (approximately 3 lbs) Sweet Potatoes (about 5 large), peeled
  • 2 tbsp (30 ml) Olive Oil, for greasing the dish
  • Salt and Black Pepper, to taste
  • 1 cup (240 ml) Heavy Cream (Double Cream)
  • ½ cup (120 ml) Crème Fraîche (Full fat)
  • 2 large Cloves Garlic, minced or grated
  • 1 tbsp (15 ml) Fresh Thyme Leaves, stripped from the stem
  • 1 tsp (5 ml) Fresh Rosemary, finely chopped
  • ½ tsp (2.5 ml) Ground Nutmeg
  • 1 tsp (5g) Fine Sea Salt
  • ½ tsp (2.5g) Black Pepper
  • ½ cup (50g) Gruyère Cheese, freshly grated (or high-quality sharp cheddar)
  • 2 tbsp (30g) Unsalted Butter, cut into small dots

Instructions:

  1. Preheat oven to 375°F (190°C). Lightly grease the 9 x 13 inch baking dish with olive oil. Using a mandoline or very sharp knife, slice the peeled sweet potatoes uniformly thin—ideally ⅛ inch (3 mm) thick. Consistency is key here.
  2. Prepare the Cream Base: In a large mixing bowl, whisk together the heavy cream, crème fraîche, minced garlic, thyme, rosemary, nutmeg, salt, and pepper until well combined.
  3. Assemble the Tian: Add the sliced sweet potatoes directly into the cream base mixture. Toss gently until every slice is coated. Arrange the sweet potato slices in the prepared dish, slightly overlapping them in neat rows or diagonal lines.
  4. Pour any remaining cream mixture evenly over the top of the dish. Sprinkle the grated Gruyère cheese evenly over the layered sweet potatoes and dot the surface with the small pieces of unsalted butter.
  5. Bake the Tian: Tightly cover the baking dish with aluminium foil. Bake for 35 minutes. Remove the foil and return the dish to the oven, uncovered. Bake for another 20–25 minutes, or until the top is deeply golden brown and the sweet potatoes are completely tender when pierced with a fork.
  6. Rest and Serve: Remove the Sweet Potato Tian from the oven and let it rest on a wire rack for 10 minutes. This critical resting period allows the Tian to set up. Garnish with fresh thyme or rosemary before serving piping hot.