Cook squash in a saucepan of boiling salted water for 3 minutes. Add the tortellini; cook according to package directions and until squash is tender. Drain pasta and squash; set aside. Heat oil in a skillet over medium- high. Add prosciutto, cook until crisp, then drain on a paper towel-lined plate. Return skillet to burner (with drippings); reduce heat to medium. Melt butter in the skillet. Add sage sprig and cook until butter browns, about 4 minutes; remove sage and discard. Stir in wine and sugar; cook 30 seconds, then add reserved squash, tortellini, and prosciutto. Toss to heat through. Off heat, finish with lemon juice, parsley, and pepper.