Stir together the olive oil, lemon juice, garlic, rosemary, and salt and pepper in a large bowl. Add chicken breasts (lightly beat with meat tenderizer if desired) to the bowl. Stir together and refrigerate 15 to 30 minutes to marinate chicken.

Combine ground allspice, coriander or cumin, and cinnamon in a small bowl or ramekin and set aside.

Season pounded/marinated chicken breasts with salt and pepper on one side only. Dredge lightly in the flour (you won't use all of it).

Turn oven on low. Heat a wide, heavy skillet over high heat and add the oil. When oil is hot, place one or two pieces of chicken in the pan, however many will fit without crowding the pan. Cook for approx 2 minutes, until bottom is browned in spots. Turn over and brown on other side, about 2 minutes. (Do not overcook or chicken will be dry.) Transfer to a platter or sheet pan and keep warm in the oven. If there is more than a tablespoon of fat in the pan, pour some (but not all) of it off into a jar or bowl.

Turn burner heat down to medium. Add ground spices to the pan and when they begin to sizzle add spinach and salt and pepper to taste. Cook, stirring with a wooden spoon and deglazing the bottom of the pan with the liquid that comes off the spinach, until spinach wilts, 2 to 3 minutes. Remove to a platter or to plates and serve with the chicken.