Remove and discard giblets and neck from chicken. Rinse chicken with cold water; pat dry. Trim excess fat. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat.
Combine 2 tablespoons chopped oregano and garlic cloves. Rub seasoning mixture under loosened chicken skin and drumsticks. Carefully place basil leaves under loosened skin. Tie ends of legs with cord. Lift wing tips up and over back; tuck under chicken.
Place chicken, breast side up, on a broiler pan coated with cooking spray. Pierce skin several times with a meat fork. Arrange potatoes on rack around chicken. Coat the chicken and potatoes with cooking spray. Sprinkle the chicken and potatoes with 1 tablespoon oregano, salt, and pepper. Insert a meat thermometer into the meaty part of thigh, making sure not to touch bone.
Bake at 450 degrees for 30 minutes. Reduce the oven temperature to 350 degrees (do not remove chicken from oven); bake an additional 45 minutes or until thermometer registers 180 degrees. Cover chicken loosely with foil; let stand 10 minutes. Discard skin. Remove chicken from pan; place on a serving platter. Serve with roasted potatoes.