For the blue cheese butter

1. Using a fork, mash in and combine blue cheese, garlic, butter, and rosemary in a small bowl. Mix until fully incorporated. Place in the refrigerator for about 10-15 minutes and remove 5 minutes before serving.

For the ribeye

1. Preheat the oven to 415°F. Remove steak from the fridge 30 minutes before cooking, this is to bring the steak to room temperature and ensure your cooking times are more accurate. Season both sides liberally with salt and pepper.
2. Add oil to an oven-safe cast iron skillet and turn up high, allowing the skillet to become hot first. Place the ribeye face down and sear undisturbed for 2 minutes. Flip the ribeye and sear for an additional 2 minutes. This will give your steak a nice seared edge.
3. Transfer your skillet directly to the oven. [WARNING] skillet may be hot, handle with oven mitts. For rare, bake for 4 minutes. Medium rare, 5-6 minutes. Medium, 6-7 minutes. Medium well, 8-9 minutes. Remember, depending on the size of the steak, the more or less time it will take. This recipe is ideal for a 20-24 ounce bone-in ribeye that is roughly 1 inch thick. Transfer ribeye from the skillet and set on a plate, top with a spoonful of blue cheese butter, and let rest for 5 minutes before serving. This is important to bring your steak to its final serving temperature.