6 medium starchy potatoes, about 2 1/2-3 pounds, peeled and cut into thick slices
4 medium or 2 large parsnips, about 1 pound, peeled and thickly sliced
4 tablespoons extra virgin olive oil (EVOO), divided
1 pound mushrooms, crimini or button, quartered
2 tablespoons freshly chopped thyme
Coarse black pepper
1 1/2 pounds ground beef sirloin
1 large fresh bay leaf
2 carrots, peeled and chopped into 1/4-inch dice
2=3 ribs celery with leafy tops, chopped
1 large or 2 medium onions, finely chopped
3-4 cloves garlic, finely chopped
2 rounded tablespoons flour
2 tablespoons tomato paste
About 3 tablespoons Worcestershire sauce
1 cup dry red wine or dark beer
2 cups beef stock
1 cup packed watercress, finely chopped
1 cup milk
3 tablespoons butter or sour cream
2 cups shredded or crumbled very sharp white cheddar cheese
Freshly grated nutmeg, to taste
Place potatoes and parsnips in a pot and cover with cold water. Bring to a boil and season with salt, cook to tender. Preheat oven to 400°F.
Heat a large Dutch oven over medium-high heat with a couple tablespoons EVOO, 2 slow turns of the pan. Add mushrooms and brown completely. Season with thyme, salt and pepper and remove to a plate.
Add 1 turn of the pan EVOO to the pot and heat until it begins to smoke. Add meat and caramelize until deep brown. Remove to a plate and add remaining tablespoon oil, another turn of the pan. Add bay, vegetables and garlic, and reduce heat to medium. Cook 12-15 minutes, until tender, then sprinkle in flour. Cook a minute then stir in tomato paste and Worcestershire. Deglaze the pot with wine or beer and stir in stock. Reduce heat and let simmer to thicken and combine flavors. When ready to assemble casserole, wilt in ‘cress and remove bay.
Drain and mash potatoes and parsnips with milk and butter or sour cream. Melt in cheese and season potatoes and parsnip mash with salt, pepper and nutmeg to taste.
Place meat and mushrooms in a large casserole dish and top with the potatoes. Bake 20 minutes or until brown.
For a make-ahead meal, let assembled casserole cool completely then refrigerate for up to 4 nights. Bake covered for 45 minutes at 375°F and 20-30 minutes longer uncovered, until brown.
To freeze, let assembled casserole cool, then wrap in plastic then foil. Defrost casserole one day ahead and cook for 1 hour at 375°F covered with foil, then 20-30 minutes more uncovered, until brown.