Cappellaci con Zucca

INGREDIENTS

• 1 tablespoon olive oil
• 1 butternut squash (3 1/2 to 4 pounds), halved lengthwise and seeded
• 1 1/4 cups freshly grated Parmigiano-Reggiano cheese, plus more for garnish
• 2 amaretti cookies, preferably Lazzaroni, finely crushed
• Freshly ground black pepper
• Pinch of freshly ground nutmeg
• 1 1/4 pounds pasta sheets
• 1/2 cup (1 stick) unsalted butter
• Coarse salt
• 12 slices prosciutto, thinly sliced
• 1/4 cup hazelnuts, roasted, peeled, and finely chopped