How to Make It
In a large heavy skillet, heat 2 tablespoons of the oil until almost smoking. Season the chicken legs with salt and pepper and cook over moderately high heat until well browned, about 5 minutes per side. Remove the chicken from the pan and pour off the fat.
Heat 2 more tablespoons of oil in the skillet. Add the onion and 3 of the garlic cloves and cook over moderately high heat, stirring, until softened, about 7 minutes. Add the chicken to the skillet with the tomatoes, wine and rosemary; season with pepper and bring to a boil. Reduce the heat and simmer until the chicken is cooked through, 20 to 25 minutes. Season with salt. Transfer the chicken to plates and keep warm.
Meanwhile, in a food processor, pulse the olives with the remaining 2 tablespoons of oil and 1 garlic clove to a coarse paste. Stir the olive paste into the pan sauce and warm over moderate heat. Spoon the sauce over the chicken and serve.