How to Make It
Heat oven to 450° F. Place the prosciutto in a single layer on a rimmed baking sheet and bake until beginning to darken, 10 to 12 minutes. Let cool (the prosciutto will crisp as it cools), then crumble.
Meanwhile, bring a large saucepan of salted water to a boil. Add the peas and cook until tender, 5 to 7 minutes (1 to 2 minutes if frozen). Drain and rinse under cold water to cool.
In a large bowl, toss the peas with the oil, Feta, scallions, prosciutto, and ¼ teaspoon each salt and pepper.