Preheat oven to 400 degrees F (200 degrees C). Lightly grease an 8x12 inch casserole dish.
Heat oil in a skillet over medium heat and cook hash browns until golden. Spread hash browns over bottom and sides of casserole dish to form a crust. In a separate skillet over medium heat, cook turkey until lightly brown. Mix in onion and cook until tender. Place broccoli in a microwave safe bowl and cook in microwave 4 to 5 minutes on High, or until tender. Spread turkey, onion and broccoli over hash browns in the casserole dish.
In a bowl, mix cream of mushroom soup, cream of celery soup, Cheddar cheese, milk, garlic powder, pepper and seasoned salt. Pour over casserole.
Bake 25 minutes in the preheated oven, until bubbly. Garnish with chopped tomatoes to serve.
