Preheat oven to 375°F.
1. In a large pot, bring potatoes and water to a boil. Cover. Reduce heat and cook 10 to 12 minutes or until soft.
2. Spray a large skillet with nonstick cooking spray. Place the skillet over medium-high heat and add canola oil. When oil is hot, add onion, garlic, ground beef, carrots, and mushrooms. Cook 4 to 5 minutes or until beef is cooked through.
3. Add Worcestershire sauce, thyme, oregano, pepper, tomato paste, and broth. Bring to a boil. Cover. Reduce heat to simmer and cook 10 minutes.
4. Add peas.
5. In a small bowl, combine cornstarch and water. Add to skillet and stir 1 to 2 minutes to thicken. Spray a deep medium-size baking dish with nonstick cooking spray. Remove the vegetable mixture from the skillet and pour into the dish. Set aside.
6. Drain water from potatoes when cooked. Add the milk, salt, onion powder, and cheese. Mash mixture with a potato masher or fork until smooth.
7. Spoon evenly on top of the vegetable mixture. Bake for 20 to 25 minutes.
Makes 4 servings.