Farfalle with Peas, Tarragon and Cream

1½ tbs. unsalted butter
⅔ cups minced green onions (scallions), white and pale green parts only
½ cup heavy cream
½ cup chicken stock
1 tsp. minced fresh tarragon
salt and freshly ground black pepper
2½ cups freshly shelled English peas
1½ pounds dried farfalle or linguini
2 oz. prosciutto di Parma, finely minced
½ cup freshly grated Parmesan Cheese

Melt butter in a 12 inch skillet over moderately low heat. Add green onions and sauté until softened, about 3 minutes. Add cream, stock, tarragon and salt and pepper to taste. Bring to a simmer and adjust heat to maintain a simmer. Cook a few minutes until reduced to a sauce-like consistency. It should be thick enough to coat the spoon. Keep warm.

Boil Fresh peas in a large quantity of salted water until tender, 5 to 8 minutes. Drain. Add peas to sauce.

Cook pasta in a large pot of boiling salted water until al dente. Just before pasta is done, add prosciutto to sauce. Drain pasta, reserving about ½ cup of the cooking water. Transfer to a large warm bowl. Add sauce and toss gently. Add cheese and toss again, adding some of the reserved water if needed to thin the sauce.  Serve.