Pat the ribeye steak dry with paper towels. Season generously on all sides with kosher salt and black pepper. Allow the steak to sit at room temperature for at least 30 minutes, or up to 1 hour, to ensure even cooking.

Preheat your oven to 250°F (120°C). Place the seasoned steak on a wire rack set inside a baking sheet.

Bake for 45-60 minutes, or until the internal temperature reaches your desired doneness. For a well-done steak, target 145-150°F (63-65°C). Use a meat thermometer inserted into the thickest part of the steak.

Once the desired internal temperature is reached, remove the steak from the oven.

Heat a heavy-bottomed skillet (cast iron works best) over high heat until it's smoking hot, about 5 minutes. Add olive oil to the pan.

Carefully place the steak in the hot skillet. Sear for 2-3 minutes per side until a deep, golden-brown crust forms. If using, add butter, rosemary, and smashed garlic cloves to the pan during the last minute of searing, basting the steak with the melted butter.

Remove the steak from the skillet and transfer it to a cutting board. Let it rest for at least 10 minutes before slicing against the grain. This allows the juices to redistribute, ensuring a tender and flavorful steak.

Slice and serve immediately.