Special equipment: an ovenproof skillet and butcher's string 8 by 8 by 2-inch baking pan and parchment paper
Preheat the oven to 400 degrees F.
Tie the beef with butcher's string and rub with the olive oil. Combine the rosemary, parsley, thyme, and garlic and pat the mixture on the beef. Season the beef with salt and pepper.
Over high heat sear the beef in an ovenproof skillet, turning to brown on all sides, about 5 minutes. Place the skillet directly into the oven and roast the beef for 20 to 25 minutes. Let the beef rest for 10 minutes before removing the string and slicing.
Preheat the oven to 375 degrees F.
Line the bottom and sides of an 8 by 8 by 2-inch baking pan with parchment paper. Rub the parchment paper with butter and a little bit of the garlic. Lay the potatoes in overlapping rows to cover the bottom of the parchment paper. Sprinkle with some of the cheese and garlic. Repeat the layering process until all the potatoes, cheese and garlic have been used.
Whisk together the eggs, cream, salt, pepper, and nutmeg. Pour the egg mixture over the potatoes. Press down on the potatoes to distribute the egg mixture. Cover the dish with parchment paper and bake for 1 1/2 hours. (Remove the parchment paper from the top for the last 20 minutes to brown the top).
Allow the flan to rest for at least 15 minutes before turning out of the pan and cutting into serving sizes. This dish is best made a day ahead, then portioned and reheated in 400 degree F oven for 10 to 15 minutes.
In a medium pot heat the olive oil over medium-high heat, add the onions, and cook for 7 minutes until soft, stirring frequently. Stir in the sugar and salt, and cook for a further 7 minutes. Add the port and vinegar, and bring to a boil. Reduce the heat to medium-low and simmer for 30 minutes or until thickened. Stir in the thyme. Keeps for 1 week stored in the refrigerator in an airtight container