Preheat the oven to 325°F. Bring the top rack lower to allow the turkey to be put into the oven in the lower half of the oven.
After your turkey has come close to room temperature. Remove any giblets inside the turkey cavity (you can use these to make turkey gravy.) Pat the entire turkey dry with a paper towel. The bird needs to be as dry as possible. Add turkey to a roasting pan with a rack.
In a small mixing bowl, add the butter, olive oil, 2 chopped garlic cloves, zest and juice from 1 ½ lemons, parsley, 2 Tablespoons chopped sage leaves, 1 Tablespoon chopped rosemary leaves and 1 Tablespoon chopped thyme leaves. Mix ingredients well to create an herb butter.
Lift a little of the skin covering the breast and gently push your fingers under the skin of the turkey as far as you can without ripping the skin. It’s important to keep the skin from tearing so don't rush this step.
Take half of the herb butter and stuff under the skin. Evenly spread the butter underneath the skin (this is why it’s important to keep the skin intact, you want to keep the butter inside adding moisture).
After that, take the remaining butter and spread all over the outside of the turkey. Over the breasts, legs and wings.
Lift the bird and salt and pepper inside the cavity. Stuff the remaining lemon halves, onion halves, the rest of the herbs and garlic cloves (peeled and smashed) inside the turkey.
Tie the two legs together with kitchen twine. This step is optional if you don’t have any. It just makes for a prettier presentation after roasting but is not absolutely necessary.
Put the turkey into the oven, uncovered, and roast for 3 ¾ - 4 ¼ hours. The turkey will be done when the thermometer reads an internal temperature between 165°F-170°F (remember to insert the thermometer into the thickest part of the turkey without touching a bone).
Remove the turkey and make a tent out of foil to cover.
Allow the turkey to rest in its own steam for a minimum of 30 minutes. This is important to keep a nice moist turkey.
Carve, removing legs first, then the breasts (keeping them whole), then slicing after.