Remove the steaks from the refrigerator 20 minutes before cooking so they come to room temperature.
Preheat the oven to 425 F. Season the steaks with salt and pepper on both sides.
Melt the butter and olive oil in an oven-proof pan over medium-high heat and add the rosemary and garlic. Saute for a couple of minutes until fragrant. Add the steaks and cook for 2-3 minutes per side or until a nice dark-brown crust has formed. Remove the garlic and rosemary, spoon some of the butter and oil over the steaks and crumble blue cheese on top. Place the pan in the oven and cook for an additional 2 to 5 minutes or until it reaches desired doneness.*
Remove the steaks to a plate and let rest for 5 minutes. Drizzle the steaks with any accumulated juices, sprinkle with chopped parsley, and serve with roasted potatoes and mixed greens (recipe below).
*The best way to test a steak’s doneness is with a meat thermometer (I especially like the digital ones): for medium-rare steaks (bright pink interior) the internal temperature should be at 130 – 135 degrees F. For medium steaks, (slightly pink) you want 140 – 145 degrees F, and for medium-well (no pink), you want 150 – 155 degrees F. I like mine medium-rare, so I usually sear 3 minutes the first side, 2 minutes the second, and finish in the oven around 3 more minutes.