Ingredients:

  • lbs Sweet Potatoes, peeled
  • Tbsp Unsalted Butter, for browning
  • ½ cups Heavy Cream
  • ½ cup Whole Milk
  • medium Shallots, very finely minced
  • Tbsp Fresh Sage, finely chopped
  • ½ tsp Nutmeg, freshly grated
  • tsp Fine Sea Salt
  • ½ tsp Black Pepper
  • cup Gruyère or Sharp White Cheddar Cheese, finely grated (optional)
  • ½ cup All-Purpose Flour
  • ½ cup Pecans, roughly chopped
  • Tbsp Brown Sugar, packed
  • Tbsp Unsalted Butter, cold and cubed (for topping)
  • A pinch of Salt (for topping)

Instructions:

  1. Preheat oven to 375°F (190°C). Peel and uniformly slice sweet potatoes very thinly (ideally 1/8 inch or 3mm thick) using a mandoline or sharp knife. Set aside.
  2. In a small skillet, melt the 4 Tbsp of butter over medium heat until it foams and brown bits form at the bottom (nutty aroma). Immediately remove from heat. Sauté the minced shallots and chopped sage in the browned butter for 1 minute until fragrant.
  3. Whisk the heavy cream, milk, nutmeg, salt, and pepper into the brown butter/shallot mixture. Stir in the grated cheese, if using.
  4. Arrange half the sweet potato slices tightly in a buttered 9x13 inch baking dish, overlapping slightly. Pour half the cream mixture evenly over the top. Layer the remaining potatoes, then pour over the remaining cream. Press down gently.
  5. Cover the dish tightly with foil or parchment paper. Bake for 45 minutes. Remove the covering and bake for an additional 15–20 minutes, or until potatoes are tender when pierced.
  6. While the gratin bakes, prepare the crumble: In a bowl, combine flour, pecans, and brown sugar. Cut in the 3 Tbsp of cold, cubed butter using your fingertips or a pastry blender until coarse crumbs form. Add a pinch of salt.
  7. Sprinkle the pecan crumble evenly over the top of the gratin. Return to the oven for 10 minutes. Switch the oven to the broiler (grill) setting for the final 2–3 minutes, watching carefully, until the topping is deep golden brown and bubbling.
  8. Allow the gratin to rest for 10–15 minutes before slicing and serving to ensure the structure sets.