Preheat oven to 375 degrees F. Rinse inside of chicken; pat dry with paper towels. Skewer neck skin of chicken to back; set aside. Peel away dry outer layers of skin from heads of garlic, leaving skins and cloves intact. Separate cloves. Peel and mince four of the cloves. Set remaining cloves aside.

In small bowl, combine minced garlic, 1 tablespoon of the oil, 1 tablespoon thyme, cracked black pepper, and 1/4 teaspoon salt. Sprinkle mixture over chicken; rub in with your fingers.

Place six garlic cloves in cavity of chicken. Tie legs to tail. Twist wing tips under back. Place onion and remaining garlic cloves in bottom of shallow roasting pan. Drizzle with remaining oil.

Place chicken, breast side up, on onion mixture in pan. Roast for 1 1/4 to 1 1/2 hours or until drumsticks move easily in their sockets and chicken is no longer pink (180 degrees F). Remove chicken from oven. Using slotted spoon, remove onion mixture from pan. Cover chicken loosely with foil; let stand for 15 minutes.

For sauce: Carefully squeeze 10 of the roasted garlic cloves from skins into blender or food processor. Add roasted onion and 1/4 cup of the half-and-half. Cover and blend or process until smooth. Transfer to small saucepan. Stir in flour. Add remaining half-and-half, the 1 teaspoon thyme, 1/4 teaspoon salt, and ground black pepper. Cook and stir over medium heat until slightly thickened and bubbly. Cook and stir for 1 minute more. Serve chicken with sauce and remaining garlic cloves. Makes 6 (4 ounces cooked meat, 1/3 cup sauce, and 1/4 cup vegetables) servings.