Slice chicken breasts horizontally to flatten. Pound with a meat mallet to flatten chicken breasts. Heat oil in a skillet over medium heat. Combine flour and dried seasonings. Dip chicken breasts in flour mixture, and heat in skillet until browned on both sides (usually 5 minutes per side). Place chicken on plate in preheated 200 degree oven. Add a couple of tablespoons leftover flour mixture and cook for a minute. Add sherry, water, lemon juice, chicken base, capers, and garlic and cook until thickened. Add chicken breasts back to pan and cook in sauce for several minutes. Add spinach and put lid on pan. Cook for several minutes until spinach is just heated through. Toss spinach in sauce and adjust the seasoning.