Preheat oven to 400-degrees. Coat a pie plate or 6 individual casserole dishes with cooking spray.
In large, nonstick skillet, cook ground beef and onion until beef is cooked through (about 6 minutes). Stir in the salt-free seasoning and smoked salt. Spread beef mixture evenly in the prepared dish or dishes. Sprinkle cheese evenly over the top of beef mixture.
In medium-sized bowl, whisk together whole wheat flour, baking powder, and seasoned salt. Whisk in the oil until evenly combined. Pour in the milk and the beaten eggs all at once and stir until blended (it will be a bit runny). Pour this batter evenly over the beef and cheese mixture in the dish or dishes.
Dot the top of the cheeseburger pie(s) with the diced tomatoes. Bake for 25 minutes (20 minutes for individual dishes) or until knife inserted into the center comes out clean. Serve individual containers or cut large cheeseburger pie into wedges and serve with fun garnishes and condiments!