Creamy Fettuccini With Citrus, Prosciutto, and Herbs

Ingredients

• Salt
• 1 carton (8 ounces) mascarpone cheese or creme fraiche or 1 cup heavy (whipping) cream
• 1 egg yolk
• 1/3 cup (1.5 ounces) finely grated Parmesan or Asiago cheese
• Finely grated zest of 1 small lemon
• Finely grated zest of 1/2 small orange
• 1/4 teaspoon freshly ground black pepper
• 1/8 teaspoon crushed red pepper flakes, optional
• 1 package (3 ounces) thinly sliced prosciutto or 6 thin slices ham
• 1/4 cup thinly sliced herb leaves, such as a combination of Italian parsley, basil, mint
• 2 to 4 tablespoons finely shredded parmesan or asiago cheese, for serving
• 12 ounces dried fettuccine noodles