Julienne the half onion and set aside.
Season both sides of ribeye steaks generously with salt and pepper.
Sear steaks in a hot cast iron skillet until a nice crust forms.
Baste steaks with 4 tbsp of butter, add a head of garlic (cut top off, face down), and cook for 1-2 minutes.
Add onions to the skillet, season to taste, and sauté.
Deglaze the pan with about 2.5 cups of beef broth, until it almost covers the steaks. (do not completely cover the steaks, we are braising it!)
Cut the French baguette, make garlic bread buns using garlic butter spread.
After 35-40 minutes, remove steaks, let them rest for 5 minutes, and season au jus to taste with salt and pepper.
Slice the steak and assemble sandwiches with garlic bread, smoked provolone, and sautéed onions.
Broil sandwiches until the cheese melts.
Top with fresh parsley and serve with au jus for dipping.