Remove the steaks from the refrigerator.
Pat them dry with paper towels and season generously on all sides with salt and pepper.
Let them sit at room temperature for 30 minutes.
Preheat your oven to 275°F / 135°C.
Place a wire rack inside a foil-lined baking sheet.
Arrange the steaks on the wire rack and bake for 20-25 minutes, or until an instant-read thermometer inserted into the thickest part registers 125°F / 52°C for medium-rare.
Remove from the oven and let the steaks rest on the rack for 15 minutes.
Heat a cast-iron skillet over medium-high heat until it's very hot.
Add the butter; it will melt and foam. Carefully place the steaks in the skillet and sear for 60-90 seconds per side to develop a deep brown crust.
During the last 30 seconds of searing, add the rosemary sprigs and minced garlic to the pan. Tilt the skillet and use a large spoon to baste the steaks continuously with the fragrant, browned butter.
Serve immediately.