Place a large pot of salted water on the stovetop and turn heat to high. While waiting for water a boil, peel and cube potatoes. Carefully and gently add cubes to boiling water. Reduce heat, cover and simmer for 20 minutes. Once soft, drain potatoes and set aside.
Peel and dice onion and carrots.
Place a large sauté pan on the stove top and turn heat to medium. Add hamburger meat and allow it to fully brown. (Tip *I recommend using a 2.5 quart sauté pan, or larger. You'll be adding all other ingredients to this pan so you need adequate space. You can also use a large pot instead of a sauté pan.)
Once your hamburger has completely browned, drain excess fat from the meat and return it to the sauté pan. Place pan back on the stovetop and reduce heat to medium low.
Add diced onions and carrots. Allow onions, carrots and hamburger to cook together for 5-10 minutes, stirring occasionally. Add minced garlic and sauté 30 seconds longer.
Add frozen corn, frozen peas, diced tomatoes, beef broth, red wine, bay leaf, Italian seasonings, salt and pepper. Mix well to combine.
Increase heat to medium high. Once filling mixture comes to a boil, reduce heat down to low and simmer for 15-20 minutes, stirring occasionally.
While filling simmers, finish making your mashed potatoes. Combine boiled potatoes, butter, milk and salt in a large mixing bowl. Use an electric mixer to mash potatoes until smooth.
Measure corn starch and cold water into a small bowl and whisk. Add this mixture to the simmering pie filling on the stovetop. Stir and allow the mixture to continue simmering for 5-10 more minutes, it will begin to thicken. Remove from heat.
Preheat oven to 375°F.
Transfer pie filling to a 2 - 3 quart baking dish and cover with a layer of mashed potatoes about an inch thick.
Bake for 20 minutes or until filling begins to bubble. Turn oven to the high broil setting and allow the top of the pie to brown slightly (this will not take long at all, keep a close eye on the pie during broiling).
Remove pie from the oven and let it cool for 10-15 minutes before serving. Add parsley flakes on top, if desired.
Serve and enjoy!