Preheat the oven to 400 degrees F.
Grease a porcelain souffle dish with the butter.
In a sauce pot, bring the garlic and cream to a simmer. Season with salt and white pepper. Simmer for 15 minutes, or until the cream has reduced by 1/4 and has slightly thickened. Whisk in the cheese.
Season the potatoes with salt and white pepper. Layer the potatoes in the souffle dish, alternating the white potatoes, sweet potatoes and red potatoes. You should have a total of six layers. Remove the garlic from the cream and cheese mixture and pour over the potatoes. Cover the souffle dish with aluminum foil and place in the oven. Bake for 30 to 35 minutes. Remove the foil and continue cooking for 10 minutes, or until the top is golden brown. Cool the gratin for 10 minutes before serving.
Increase the oven temperature to 450 degrees F.
Season the roast with oil and Creole seasoning. Place in a roasting pan and put into the oven. Roast for 30 minutes. Reduce the heat to 400 degrees F. and continue to cook for 1 hour for medium rare. Remove from the oven and allow to rest for 10 minutes before serving.
Serve each steak with a piece of the gratin.