To make the sauce, melt the butter in a pan set over medium-low heat.
Add the garlic and rosemary and cook until the garlic softens. (Approximately 1-2 minutes)
Pour in the cream and lemon juice.
Allow to simmer for 5 minutes until the sauce has thickened slightly and coats the back of a spoon.
Remove from the heat and add the cheese. Stir until the cheese has melted then season to taste with salt and pepper.
To make the steak, pat the steak dry with paper towels then season generously with salt.
Heat a large cast iron pan or griddle pan over high heat.
Add the steaks and cook until well-browned on both sides. Once flipped, add the butter, garlic and rosemary and baste the steak with the butter. I cook my steaks for 2-3 minutes per side until they are medium rare.
Remove from the pan and allow to rest for at least 5 minutes before serving with the Gorgonzola sauce.