Take the steaks out of the refrigerator about 30 minutes before cooking. Cold meat will seize in it hits high heat suddenly so for the best results, remember to let it warm up.
When ready to start cooking, pat each steak dry with a paper towel all around.
Season steaks generously with salt and pepper on all the sides.
Preheat the oven to 450°.
Sear the steak
Make sure that your cast iron skillet is seasoned well before every use. Preheat skillet on stove-top, over medium-high heat and add a little bit of oil to the bottom.
Add steaks to the hot skillet and sear for 45-60 seconds on each side.
Finish in the oven
Once both sides have been seared, insert the leave-in thermometer through the side of the steak, towards the middle. Move the skillet into the pre-heated oven.
Set thermometer to the desired temperature. *If you are not using a leave in thermometer, you will need to manually take the temperature of the steak. Take the skillet out of the oven and close the oven door. Take the temperature by inserting thermometer through the side of the steak, towards the middle.
Flip the steaks onto the other side when they are getting about 15-20 degrees away from your desired temperature. (About half way through cooking.)
Once steaks reach desired temperature, take them out of the skillet immediately and let the steaks rest for about 5 minutes before cutting it. You can let steaks rest on the cutting board or on the plate.
Add slices of butter to the top of each steak while it's resting.