Preheat oven to 400*. Spray 9x13 pan with non-stick cooking spray and set aside
Place diced potatoes in a large pot and cover with water. Bring to a boil and cook until potatoes are tender. Drain and set aside.
In a large skillet, brown the ground beef with the diced onion. Season with the salt, pepper, thyme, rosemary, and garlic powder; brown until cooked through.
Add the frozen mixed veggies into the meat mixture.
in a small bowl, whisk the beef broth and corn starch or flour together until smooth. Pour over the meat mixture, drop in beef bouillon cube, and simmer until thickened; stirring regularly. Once gravy is thickened, pour the meat mixture into bottom of the prepared 13x9 pan.
Now, prepare your mashed potatoes by mashing the cooked potatoes with the butter, milk, salt, pepper, garlic powder, and parmesan cheese. Mash until smooth. NOTE: keep potatoes stiff and firm, NOT creamy, so that they hold up to the meat layer while cooking. Spread mashed potatoes on top of the meat layer and top with the grated cheddar cheese.
Bake at 400* for 45-50 minutes or until potatoes are lightly browned and meat mixture is bubbling. Let stand for 5-10 minutes; serve and ENJOY!
