Toast Hazelnuts: Preheat the oven to 375°F. Spread hazelnuts on a baking sheet and toast for 15 minutes. Rub them in a kitchen towel to remove skins, then chop and set aside.
1/2 cup hazelnuts
Prepare the Filling: Cut the butternut squash in half, rub the flesh with olive oil, and place cut-side down on a baking sheet. Roast for 30–35 minutes or until fork-tender. Let cool, scoop out the flesh, and puree in a food processor, adding water if needed.
1 medium butternut squash, 1 tablespoon olive oil, 2 –3 tablespoons water
Melt butter in a skillet: Heat 1 tablespoon of unsalted butter in a large skillet over medium heat. Once melted and foaming, add half the minced shallots and sauté for 1 minute until fragrant. Stir in the butternut squash puree and cook for 2 minutes, stirring frequently. Season with salt and pepper, then stir in the heavy cream and cook for an additional 2 minutes. Remove the skillet from heat and mix in the Parmesan cheese and nutmeg until well combined. Let the mixture cool.
1 tablespoon unsalted butter, 6 tablespoons minced shallots, 1/4 teaspoon kosher salt, 1/4 teaspoon freshly ground black pepper, 3 tablespoons heavy cream, 1/4 cup grated Parmesan cheese, 1 pinch ground nutmeg
Fill the Ravioli: Dust wax paper and a baking sheet with flour. Lay out 12 wonton wrappers. Add 1 teaspoon of filling to the center of each. Brush edges with egg wash, cover with another wrapper, and press to seal, removing air bubbles. Repeat until all wrappers are used, dusting with flour as needed.
1/2 cup all-purpose flour, 48 –50 wonton wrappers, 1 large egg
Make the White-Wine Sauce: Melt 1 tablespoon butter in a saucepan. Sauté the remaining shallots for 2 minutes. Add wine, cream, broth, and lemon juice. Simmer for 10 minutes until reduced by half. Whisk in remaining butter, one tablespoon at a time. Stir in sage and set aside.
5 tablespoons cold unsalted butter, 1/2 cup dry white wine, 1/2 cup heavy cream, 1/2 cup chicken broth, 1 tablespoon fresh lemon juice, 2 tablespoons minced fresh sage
Cook Ravioli and Serve: Bring a large pot of salted water to a low boil. Add ravioli in batches, cooking for 4 minutes. Drain with a slotted spoon, transfer to plates, and top with sauce and hazelnuts.