*If you happen to have leftover mashed potatoes, skip to step 2.Boil diced potatoes in salted water until soft, about 30 minutes. Preheat oven to 400°. Butter large casserole dish.
In large skillet, heat 1T oil over medium-high heat. Add chopped mushrooms. Sauté mushrooms until soft and brown. Add ¼ cup red wine (or beef broth) to the hot pan, stirring and scraping the pan till all the liquid cooks off. Remove mushrooms to a plate. Add 1T remaining oil to the skillet and heat to medium.
Saute carrots until beginning to soften, then add onion and garlic.
When onions are soft add ground meat and brown, breaking meat into large chunks.
When meat is browned, season with salt, pepper and thyme. Add mushrooms, peas and 1T butter.
Sprinkle mixture with flour and stir. Then add tomato paste, Worcestershire and remaining ½ cup red wine (or beef broth).
Cook and stir mixture for several minutes. Add beef stock and simmer until sauce is thick and somewhat reduced.
Remove from heat and stir in zucchini. Season to taste.
Pour meat mixture into casserole dish, lightly sprayed with oil.
Drain and mash potatoes with butter, cream and salt & pepper.
Spoon mashed potatoes over meat, spread and smooth the top. (At this point you can refrigerate or freeze the dish as desired. I freeze individual portions in ramekins).
Brush potatoes with a beaten egg and sprinkle with parmesan. I also like to sprinkle more thyme on top.
Bake casserole 30 minutes or until hot and bubbling and potatoes are browned. *Cook time will be longer for a cold or frozen dish.