Salt and pepper both sides of the steaks.
Grill in 2 tablespoons butter until medium rare.
Saute onions in 4 tablespoons butter over high heat.
Cook for 5 to 7 minutes, or until dark and caramelized.
Reduce heat to simmer and pour in cream.
Cook for 3 to 5 minutes, or until reduced by half.
Stir in blue cheese until melted.
Serve steaks on generous portion of sauce