2 tablespoons Savory Butter Infused Olive Oil
3 garlic cloves, peeled and minced
2 tablespoons fresh sage, chopped
1 tablespoon fresh rosemary, chopped
2 cups heavy cream
1/4 teaspoon ground nutmeg
1 teaspoon Black Truffle Sea Salt
3 lbs. sweet potatoes, peeled and thinly sliced
8oz gruyere cheese, grated
Preheat oven to 400°F and drizzle a 13x9-inch casserole or baking dish with one tablespoon of Savory Butter Olive Oil.
Place the remaining one tablespoon of oil in a medium saucepan and heat over medium. Once the oil is hot, add garlic, sage, and rosemary to the pan, and sauté for 1 minute or until fragrant. Add the cream, nutmeg, and truffle salt to the pan, whisk to combine and bring to a simmer. Simmer for 10 minutes, stirring frequently, or until the mixture has reduced slightly.
Place the eggs in a large bowl and whisk until blended and slightly frothy. Pour a thin stream of the hot cream into the bowl, whisking vigorously, to temper the eggs. Once tempered, add the remaining cream to the bowl and whisk.
Shingle a single layer of sliced potatoes on the bottom of the prepared baking dish. Lightly season the potatoes with salt and pepper and sprinkle with 1/2 cup of grated gruyere. Pour 1/2 cup of the cream mixture over the potatoes and repeat with another layer of potatoes (lightly season with salt and pepper), cheese, and cream. Finish the final layer with potato slices and pour over the remaining cream (reserve the remaining cheese for later).
Cover the baking dish with foil and place it in the oven. Bake for 40 minutes or until the sweet potatoes are slightly tender. Remove from the oven, remove the foil, and sprinkle the remaining grated cheese. Return to the oven and bake for 20-30 minutes until bubbly and nicely golden brown. Remove from the oven and set aside to rest briefly (about 5-10 minutes) before serving.