Start by removing the giblets from the cavity and patting the turkey completely dry with paper towels. This step matters more than people realize, because dry skin is what crisps up beautifully in the oven. Let the turkey sit at room temperature for about 30 minutes before roasting.
Rub the softened butter all over the outside of the turkey, and a little underneath the skin on the breast if you can reach it. Sprinkle the salt and pepper evenly over the entire bird. Drizzle the olive oil on top so the skin gets that extra crispy, golden finish.
Place the lemon, onion, garlic, rosemary, and thyme inside the turkey's cavity. These aromatics quietly perfume the meat from the inside while it roasts. Tie the legs together with kitchen twine so the turkey holds its shape and cooks more evenly.
Place the turkey breast-side up on a rack inside your roasting pan. Pour the chicken or turkey broth into the bottom of the pan, not over the turkey itself. This keeps the drippings from scorching and gives you a flavorful base for gravy later.
Roast at 425°F for the first 30 minutes to jumpstart browning, then lower the temperature to 350°F for the remaining time. A small turkey usually needs about 13 to 15 minutes per pound total. There's no need to baste constantly, just let the oven do the work.
Insert a meat thermometer into the thickest part of the thigh without touching the bone. You're looking for an internal temperature of 165°F. If the skin browns too fast before the inside is done, tent it loosely with foil.
Once it's done, move the turkey to a cutting board and let it rest for 20 minutes before carving. This resting time allows the juices to redistribute through the meat instead of spilling out the second you slice into it.