1. In a heavy 1- to 2-quart saucepan, melt the 2 tablespoons of butter over moderate heat and cook the finely chopped onions for 7 or 8 minutes, stirring frequently until they are soft but not brown.
2. Stir in the green peas and chicken stock, cover, and cook for 15 to 20 minutes.
3. When the peas are tender, add the strips of prosciutto and cook, uncovered,stirring frequently, for 2 minutes more, or until all the liquid is absorbed.
4. Taste for seasoning. Serve the peas in a heated bowl.
NOTE: One 10-ounce package of frozen peas may be substituted for the fresh peas. Defrost the peas thoroughly before using them, and add them to the onions without any stock. Cook the peas uncovered, stirring frequently, for about 5 minutes, then add the prosciutto, heat through and serve.
