Season both sides of the steak with salt and pepper. Let steak come to room temperature after seasoning. (about 1 hour) The salt will pull the moisture to the outside of the steak as the salt and pepper seeps in to season both inside and outside of the steak- this also tenderizes the steak and provides a more tender and juicy bite. Cooking the steak once it comes to room temperature will also cook it more evenly.
Heat a cast iron skillet over high heat. Preheat the oven to 350 degrees.
Add oil to the skillet. Next, add steak and sear for 5 minutes per side. Do not overcrowd the skillet, work in batches if need be. Do not press on the steak as it cooks or move it until it is time to flip.
Place seared steaks in a baking pan with a lip. Add a couple crushed garlic cloves, 1 tablespoon slice of butter, and a rosemary sprig atop each steak.
Place into the oven and bake for 5-10 minutes depending on preferred doneness of the steak. 5 minutes gave us perfect medium rare, but cooking time may vary so it is best to use a meat thermometer to determine how long the steak should finish in the oven.
Remove steak once it is 5 degrees below your desired temp and place steak onto a wooden cutting board. Keep the garlic and rosemary on the steak. Pour the melted butter over each steak from the pan and tent with foil.
Let steak rest for 7 minutes. The steak will finish cooking as it rests and the internal temperature will come up about 5-7 degrees.
Slice against the grain and serve. Enjoy!