Heat oven to 375° and adjust oven rack to middle position. Brush the inside (bottom and sides) of the skillet with canola oil.
Brown the ground chuck in a large cast iron skillet, set over medium heat, stirring often; drain and set aside. In the same skillet, crisp the bacon and transfer it to the cooked beef.
Add the onion to the skillet and cook until softened, about 4 minutes.
Return the beef and bacon to the skillet, add water, ketchup, mustard, mayonnaise, seasoned salt, kosher salt, and black pepper; stir well and heat through.
Remove the skillet from the heat.
Top the beef mixture with the cheese slices.
Unroll the dough and press into a circle large enough to cover the skillet. Place the dough on top of the cheese and spread it to the inside edges of the skillet.
Brush the top with the beaten egg and sprinkle the dough with sesame seeds.
Bake at 375°F for 25-35 minutes or until the top is deep golden brown and the burger mixture is bubbly.
To serve, place a spoonful of the pot pie onto each plate and serve with the desired hamburger toppings on the side (if toppings are placed on top of the casserole, the crust will gets soggy).