Roast the head of garlic in a preheated oven at 400°F for 20 minutes and then let cool. Season the round beef roast with salt and pepper and then sear on all sides in a large pan over medium heat. Rub the roasted garlic over the outside of the meat and let rest for 30 minutes. Make a deep pocket incision in the meat, about ¾ of the way down, making sure not to cut all the way through.
Carefully turn the piece of meat inside-out and place it over a tall, sturdy glass bottle.
For the potatoes au gratin, add the heavy cream and peeled & sliced potatoes to a saucepan over medium heat. Season with salt and pepper and let simmer for about 30 minutes, making sure to constantly stir the mixture. Once the mixture has thickened, crumble the cooked bacon into the saucepan, grate the cheese over the mixture, and stir until the cheese has fully melted.
Turn the inside-out piece of meat over so that the opening is facing up, place the meat inside of a vase, and remove the glass bottle. Spoon the potatoes au gratin into the meat pocket and secure the opening with toothpicks. Season the outside of the meat with salt and pepper and dredge in flour, egg, and garlic & herb bread crumbs. Repeat the breading process once more so that it really sticks. Heat some cooking oil in a large oven-proof frying pan over medium heat and fry the breaded, stuffed roast beef on all sides. Transfer the frying pan to a preheated oven and cook at 350°F for 1 hour 20 minutes. Let the stuffed oven roast beef rest for 20 minutes before serving.
