About one hour before cooking, remove the Boneless Ribeye Steak (16 ounce) from the fridge and pat dry with paper towels. Season generously with Kosher Salt (to taste) and Ground Black Pepper (to taste) and allow to come to room temperature. Do not let the steak remain in room temperature for more than 2 hours!
Place a deep cast iron skillet over medium-high heat.
Once the skillet is hot, pat the steak dry one more time - just removing any moisture, not the seasoning.
Then place the steak in the hot pan. After about 3-4 minutes, a nice crust should form on the steak.
Flip it over for another 3-4 minutes and check the temperature using a meat thermometer. If steak has not reached the desired temperature, keep flipping it over and checking the temperature every 2 minutes or so. Total cook time will depend on the thickness of the steak.
Just before steak reaches the desired temperature, add Unsalted Butter (4 tablespoon), Garlic (5 clove), and Fresh Rosemary (4 sprig) to pan. Let rosemary and garlic sizzle in the butter for a bit. Carefully tip the pan toward you so the butter pools, and spoon it over the steak a few times.
Remove the steak from the hot pan and allow to rest for 5 minutes before slicing and serving.