Ingredients
- 2-3 sweet potatoes ~1.5–2 lbs, peeled and sliced ⅛-inch thick
- 1 tablespoon kosher salt
- 1 tablespoon fresh thyme roughly chopped
- 4 oz Parmesan cheese shredded
- 4 oz Gruyère cheese grated
- 4 oz sharp cheddar cheese grated
- ¼ cup milk
- 1 cup heavy cream
- 2 tablespoon butter
- 2 cloves garlic
- ¼ teaspoon nutmeg
- ¼ teaspoon red pepper flakes
- 1-2 shallots thinly sliced
- ½ bag Setton Farms Tajín Seasoned Pistachios
- 2 oz Parmesan grated (for topping)
- ¼ cup chives thinly sliced
- Avocado oil for frying
- Foil for baking
Method
- Prep the Shallots
- Preheat oven to 375°F.
- In a small saucepan, heat 3 inches of avocado oil over medium heat.
- Once oil reaches 350–375°F, fry shallots until golden.
- Remove with slotted spoon, drain on paper towels, and season with salt. Set aside.
Make the Cheese Sauce
- In a medium saucepan, melt butter over medium heat.
- Add garlic and sauté for 1 minute until fragrant.
- Add milk, cream, thyme, nutmeg, red pepper flakes, and salt. Simmer gently for 10–12 minutes to reduce slightly.
- Remove from heat and stir in Gruyère and cheddar until melted and smooth. Season to taste.
Layer the Gratin
- Lightly grease a cast iron skillet or baking dish.
- Sprinkle ⅔ of the crispy shallots on the bottom. Top with ⅓ of the cheese sauce.
- Layer half the sweet potato slices in an overlapping pattern.
- Repeat with remaining shallots and ⅓ of the cheese sauce.
- Add final sweet potato layers, then pour remaining sauce on top.
- Gently tap dish to help settle sauce. Cover with foil.
Bake the Gratin
- Bake at 375°F for 45 minutes, covered.
- Uncover and bake another 15 minutes until top is bubbly.
- Finish with Pistachios and Cheese
- Pulse Tajín pistachios in food processor until finely chopped.
- Sprinkle over gratin along with the 2 oz Parmesan.
- Bake another 5 minutes or broil carefully for golden top.
Serve
- Let rest for 10 minutes. Garnish with fresh chives and serve warm.