Put the garlic in a food processor and mince. Add basil and parsley; process until finely chopped. Then add butter, 1 tablespoon olive oil, 1/4 teaspoon salt and some pepper. Process to blend. Transfer to a bowl; reserve 2 tablespoons.
Preheat oven to 350 degrees. Place the chicken on a foil-lined broiling pan. Loosen the skin and work the basil mixture over the meat and then rub onto the outside surfaces. Roast 20 minutes. While the chicken is cooking, cut the tomatoes in halves lengthwise. Place in a large baking dish or roasting pan.
Toss with 2 tablespoons olive oil, 1/2 teaspoon salt and a little pepper. Put in the oven with the chicken and roast 20 minutes. Test the chicken for doneness and continue cooking 5 to 10 minutes if necessary. If done, remove from the oven and cover with foil. Brush the tomatoes with the reserved basil mixture and continue roasting 10 minutes. Set 2 chicken breast halves and 8 tomato halves aside. Cool, cover and refrigerate. Serve the remaining chicken with the tomatoes to the side.