Remove the turkey breast from its packaging and pat the entire surface very dry using paper towels. A dry surface is critical for crispy skin. Allow the turkey breast to sit at room temperature for at least 30 minutes prior to cooking.

Preheat your oven to 425°F (220°C). Place the onion quarters (if using) and the chicken stock in the bottom of a shallow roasting pan fitted with a rack. (If you do not have a rack, you can use large carrot and celery pieces as a base.)

In a medium bowl, combine the softened butter, chopped rosemary, thyme, sage, minced garlic, lemon zest, 1 teaspoon of kosher salt, and ½ teaspoon of black pepper. Use a fork or spatula to thoroughly mix until the butter is uniform and the herbs are evenly distributed.

Gently loosen the skin over the breast meat using your fingers, creating a pocket for the butter. Take about two-thirds of the prepared herb butter and stuff it underneath the skin, massaging it across the surface of the meat. Rub the remaining one-third of the herb butter over the exterior of the turkey skin. Lightly drizzle the entire surface of the turkey with 1 tablespoon of olive oil, and season generously with additional salt and pepper.

Place the prepared turkey breast skin-side up on the rack in the roasting pan. Place the turkey in the preheated 425°F (220°C) oven and roast for 15 minutes. The high heat sets the skin and begins the crisping process.

After 15 minutes, reduce the oven temperature to 350°F (175°C) without opening the oven door. Continue roasting for another 60 to 105 minutes (1.5 to 2 hours total). If the skin begins to brown too quickly, loosely tent the turkey breast with aluminum foil. You may baste it once or twice during the last 30 minutes using the pan drippings and stock.

The turkey is finished when a meat thermometer inserted into the thickest part of the breast (avoiding the bone) registers an internal temperature of 165°F (74°C). Immediately remove the turkey from the oven and transfer it to a clean cutting board.

Tent the turkey loosely with foil and allow it to rest for a minimum of 15 to 20 minutes before carving. Slice the turkey breast meat against the grain and serve immediately, optionally drizzling with any accumulated pan juices.