For the Potato Topping:
4 large russet potatoes (about 3 pounds), peeled and cubed
2 cloves garlic, crushed
4 tablespoons butter
½ cup whole milk
½ cup sour cream
A little freshly grated nutmeg (about 1/16 teaspoon)
Salt and white pepper
2 teaspoons dry mustard
About 1 cup grated sharp white cheddar cheese
For the Meat Filling:
1 tablespoon olive oil
2 carrots, chopped
1 rib celery with leafy tops, chopped
1 onion, chopped
Salt and pepper
2 cloves garlic, chopped
1 pound each ground beef and lamb or 2 pounds ground beef
2 tablespoons fresh thyme, chopped
2 bay leaves
2 tablespoons Worcestershire sauce
2 tablespoons flour
1 tablespoon tomato paste
1 cup red wine
2 cups beef or chicken bone broth or stock
Parsley, dill and chives, finely chopped for garnish
For the topping, place potatoes in pot with cold water, bring to boil, then add salt and garlic and cook until very tender, 17 to 18 minutes. Drain and add back to hot pot.
Meanwhile, warm butter and milk in small pot.
Add warm milk to potatoes and mash. Add sour cream, nutmeg, salt, pepper and mustard, melt in cheese, then cover and set aside. Begin cooking the meat filling while potatoes are working.
Preheat oven to 375°F, with rack at center.
For the filling, heat olive oil, a turn of the pan, in a deep skillet or oven-safe casserole over medium to medium-high heat.
Add the carrots, celery and onions, season with salt and pepper and soften them 7 to 8 minutes. Add the garlic and meats and brown and crumble. Add thyme, bay leaves and Worcestershire sauce. Add flour and paste and stir, then add wine and stock, reduce heat to low and simmer 20 minutes.
Top the beef with the potatoes and smooth. You can swirl a design or stripe the potatoes with the tines of a fork if you wanna get fancy. Bake until golden brown. Top with fresh herbs.