Prep: 1. Chop onion. 2. Halve prosciutto. 3. Slice fontina. Make: 1. Heat oil in a skillet over medium heat until it shimmers. 2. Cook onion with salt and pepper, stirring occasionally, until golden, about 5 minutes. 3. Add spinach and cook, stirring occasionally, until tender, about 4 minutes. Divide between 2 plates. 4. Pat turkey cutlets dry and season with salt and pepper, to taste. 5. Heat butter in skillet over medium heat until foam subsides, then sear turkey until pale golden, 1-3 minutes. 6. Flip cutlets over and place 1/2 slice prosciutto on each. 7. Top with cheese, then cover and cook until cheese is melted and turkey is just cooked through, about 1 minute. 8. Transfer turkey to plates with spinach. 9. Add marsala to skillet and boil, scraping up any brown bits, until reduced by half, then spoon over turkey and spinach.