Heat olive oil in a saucepan over medium heat; add sliced scallions, diced celery, and 1/4 teaspoon each salt and pepper. Cook until tender. Add rice, and stir for 2 minutes or until opaque. Season with 1/4 teaspoon each salt and pepper. Add vermouth, and cook for 2 minutes or until absorbed. Add 2 1/2 cups chicken broth, 1/2 cup at a time, stirring frequently. Stir in spinach, chopped, and fresh peas; cook. Over next 10 minutes, gradually add 2 more cups broth until rice is creamy and tender. Stir in mint, lemon zest, lemon juice, and Parmesan cheese; add sliced prosciutto. Serve.