Heat oven to 400 degrees F. In small bowl, stir together 4 tablespoons of the butter, garlic, mint, 1-1/2 teaspoons of the lemon zest, oregano, 1/4 teaspoon of the salt and 1/8 teaspoon of the pepper.
With fingers, gently make a pocket between skin and meat on the breast, thighs and legs. Insert 1 tablespoon butter mixture under skin of each piece of chicken.
Place chicken on broiler pan. Roast in 400 degree F oven for 45 minutes or until internal temperature of chicken registers 180 degrees F on an instant-read thermometer inserted into the thigh.
Meanwhile, prepare orzo as package label directs, adding peas during the last 3 minutes. Drain; toss with remaining 2 tablespoons butter, 1-1/2 teaspoons lemon zest, 1/2 teaspoon salt and 1/8 teaspoon pepper. Serve with chicken and salad, if desired. Makes 4 servings.