Pat the turkey breast dry with paper towels. If the breast is uneven in thickness, butterfly or gently pound it to an even thickness of about 1 inch so it cooks uniformly.

Season

Combine kosher salt, coarsely ground black pepper, garlic powder, onion powder, and smoked paprika in a small bowl. Rub the turkey all over with the olive oil, then evenly coat with the spice mixture, pressing it into the surface so the coarse pepper adheres. Tuck thyme sprigs around or under the breast and place the halved lemon in the pan cut-side down.

Sear

Heat a large ovenproof skillet over medium-high heat until hot. Add 1 tablespoon olive oil. When the oil shimmers, place the turkey breast presentation-side down and sear without moving for 3–4 minutes, until a deep golden crust with cracked pepper is formed. Flip and sear the other side 2 minutes.

Finish in oven

Reduce heat under the pan, add the butter and allow it to melt, spooning the melted butter over the turkey for 30 seconds. Transfer the skillet to a preheated oven at 375°F (190°C). Roast until the thickest part of the breast reaches 160°F (71°C), about 12–18 minutes depending on size. Start checking at 10 minutes to avoid overcooking.

Rest and finish

Remove the skillet from the oven and transfer the turkey to a cutting board. Tent loosely with foil and let rest 8–10 minutes; carryover will bring the internal temperature to about 165°F (74°C). While resting, squeeze the roasted lemon over the turkey and sprinkle optional freshly ground white pepper for a bright finish.

Slice and serve

Slice the turkey against the grain into 1/4-inch thick slices. Spoon any pan juices into the slices. Serve warm, garnished with the roasted thyme sprigs.