Preheat the oven to 425 degrees F. Season the steaks all over with the salt and pepper. Rub them all over with the dijon mustard. Let them sit at room temperature for 15 minutes.

While the steak rests, place the asparagus on a baking sheet. Toss with the olive oil, a big pinch of salt, pepper and garlic powder. Sprinkle with the asiago cheese. Roast the asparagus for 12 to 12 to 15 minutes, until slightly golden and tender. Leave the oven on.

Heat a cast iron skillet over medium-high heat. I highly highly suggest using a cast iron skillet for this - it will get a little smoky, so be sure to use your oven vent or turn on a fan, etc!

Add the 2 tablespoons of butter to the skillet - it will begin to brown and smoke. That’s okay!

Place the steak in the skillet right away. Sear on each side, about 2 minutes per side, until deeply golden brown. Add the remaining tablespoons of butter if needed. Spoon the butter over the steak. Once you’ve seared both sides, turn off the heat.

Place the skillet in the oven and cook for about 3 to 5 minutes, for medium doneness. This will depend on the thickness of your steak, but I suggest taking the internal temperature as this will help so much! For rare, you want 120 degrees F. For medium rare, 125 to 130 degrees F. For medium, 135 to 140 degrees F and medium-well, 145 to 150 degrees F.

Let the steak rest for 5 to 10 minutes before serving. Serve with the asparagus!