1. Sprinkle chicken with onion powder, garlic powder, paprika and black pepper. Heat oil in a large frying pan. Add chicken and cook for three minutes per side.
2. Add sherry, garlic, rosemary, sundried tomatoes and capers, and cook for an additional 10 minutes, letting the sauce reduce and thicken.
3. Remove the chicken from the pan. Add spinach and cook until the spinach just starts to wilt.
4. Place the spinach on a serving platter and top with the chicken and sauce.