Creamy sweet potatoes with Gruyère, finished with crisp caramelized hazelnuts for a unique, satisfying side.
# What You’ll Need:
→ Vegetables
01 - 2.6 lbs sweet potatoes, peeled and thinly sliced (about 1/8 inch thick)
02 - 1 small yellow onion, thinly sliced
→ Dairy
03 - 1 cup heavy cream
04 - 1/2 cup whole milk
05 - 1/2 cup grated Gruyère cheese
06 - 2 tablespoons unsalted butter, plus extra for greasing
→ Seasonings
07 - 2 cloves garlic, minced
08 - 1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme
09 - 1/2 teaspoon ground nutmeg
10 - Salt and freshly ground black pepper to taste
→ Caramelized Hazelnuts
11 - 1/2 cup whole hazelnuts, toasted and skins removed
12 - 1/4 cup granulated sugar
13 - 1 tablespoon water
14 - Pinch of salt
# How to Make It:
01 - Preheat oven to 350°F (180°C). Generously butter a 2-quart baking dish.
02 - In a saucepan, combine heavy cream, whole milk, garlic, thyme, nutmeg, salt, and black pepper. Warm gently over low heat until steaming but not boiling. Remove from heat and set aside.
03 - Arrange half the sweet potato slices in an even layer in the prepared dish. Layer with half the sliced onions and one third of the Gruyère cheese. Repeat with remaining sweet potatoes and onions.
04 - Pour the warm cream mixture evenly over the layered vegetables. Scatter the remaining Gruyère on top and dot with pieces of butter.
05 - Cover the dish tightly with foil and bake for 35 minutes. Remove foil and continue baking for 15 to 20 minutes, or until the potatoes are tender and the top is golden and bubbling.
06 - While the gratin bakes, line a baking tray with parchment paper. In a small saucepan over medium heat, combine granulated sugar and water; stir until dissolved. Cook, undisturbed, until the syrup turns a deep amber, about 3 to 4 minutes. Immediately stir in toasted hazelnuts and a pinch of salt, then transfer onto the prepared tray. Let cool completely and chop coarsely.
07 - Just before serving, sprinkle the caramelized hazelnuts over the gratin for a crunchy finish.
