Warm olive oil in a large skillet, add yellow onion, carrots, and celery. Sauté until softened, about 5 minutes.
Add the ground chicken and continue to sauté for an additional 5 - 10 minutes. Then add the frozen peas, garlic, and tomato paste to the skillet. Mix and cook for an additional 2 - 3 minutes, or until the garlic is fragrant.
Deglaze with red wine, chicken stock, Worcestershire, and season with dry English mustard, stone ground mustard, onion powder, paprika, dried time, salt, and black pepper. Simmer for 10 minutes to slightly thicken.
Preheat the oven to 400F. Pour the meat and vegetable mixture in an even layer into large baking dish and cover with mashed potatoes. Create a striped design on top of the mashed potatoes by using the back of a fork. Bake for 25 minutes and serve with a sprinkle of Italian parsley.