Preheat oven to 350°F. Lay the oven bag flat on a roasting pan, ensuring it is ready for the turkey. Remove the turkey from its packaging. Take out the neck and giblet bag from the cavity. Pat the turkey dry thoroughly with paper towels and place it on a large baking pan.
Carefully, loosen the skin over the turkey breast using your hands or a wooden spoon. Be careful not to break the skin. Spread the herb compound butter evenly underneath the skin.
In a small bowl, add ¼ cup butter, melted, 2 tablespoons olive oil, and 2 tablespoons lemon juice. Rub the mixture all over the turkey, including legs and wings.
Season the entire turkey inside and outside with salt and pepper.
Stuff the cavity with the lemon halves, fresh herbs, quartered apple, and onion chunks.
Slide seasoned turkey into the parchment bag, and roll up the opening tightly, tucking any ends into the pan. For a plastic oven bag: secure the bag with the provided tie, then cut about 5-6 half-inch slits on top of the bag to allow the steam to escape.
Place the turkey (in the bag) with the roasting pan in the preheated oven and roast until fully cooked. Approximate times: 10-12 lbs — 1.5-2 hours12-16 lbs — 2-2.5 hours16-20 lbs — 2.5-3 hours20-24 hours — 3.3.5 hours) The turkey is done when the internal temperature reaches 165°F in the breast and 175°F in the thigh, Optional step: once cooked, carefully cut the bag open and drain any drippings. Place the turkey back in the oven for an additional 20 minutes to crisp the skin. Note: Be careful when opening the bag, the steam will be hot.
Let the turkey rest for about 20 minutes before carving. Serve, and enjoy.