• Preheat oven to 375 degrees.

To make the mashed potatoes:

• In a large pot, cook the potatoes in salted water until fork tender. Once the potatoes are done, let them cool a bit (just enough so you can handle them) and then peel them.
• While they are still hot, mash them in a bowl and reserve.
• In a sauce pan, heat the heavy cream and the cream cheese, whisking until the cream cheese dissolves.
• Add the heavy cream/cream cheese to the potatoes and mix well until you have a smooth mixture.
• Season with salt and pepper and reserve.

To make the beef:

• In a large skillet, heat the butter and sauté the garlic and onions until translucent.
• Add the tomatoes and the herbs and cook for about 2 minutes.
• Add the ground beef and cook until browned (about 10 minutes).
• Add the flour, the parmesan cheese and the crushed tomatoes.
• Cook until the sauce thickens slightly.
• Add the egg yolk and season with salt and pepper.
• Transfer the beef to a seasoned 12-inch cast iron skillet.
• Top with mashed potatoes and then with the mozzarella.
• Bake in over for 30 minutes or until the cheese has melted and browned.