Add the butter into the pan. Turn the heat to high. When the butter has melted, lay the beef in carefully so as to not splash the hot oil.
Add in the rosemary on the side.
After 2 minutes, using tongs, flip the beef. The beef should be nicely browned.
Cook for 2 minutes, basting the steak with the rosemary butter from the pan. Then place the pan into the oven.
Cook in the oven for 5-6 minutes, depending on your desired level of doneness.
Remove from the oven and set on the stove. Flip with tongs and baste again.
Remove the steak from the pan and set on the cutting board. Cover with foil and allow to rest for 5-10 minutes.
Slice against the grain, top with the crispy shallots and roasted garlic.
Serve hot and enjoy!