Heat a nonstick skillet over medium heat. Season the beef with the salt, pepper and onion powder, then add to the skillet and cook until browned, using a wooden spoon to bread the beef into small crumbles, about 5 to 6 minutes. Drain any liquid from the skillet. Combine the ketchup and mustard in a small bowl and mix until combined. Note that this sauce makes enough for two pizzas, so use half on each. Remember, the dough MUST be on a well-floured pizza peel (or surface) so you can simply slide the entire thing into the skillet. Spread half of the sauce onto the dough and cover it with a sprinkling of cheddar. Add half of the beef on top, then add another handful of cheese and the bacon. The bacon should only be slightly cooked so it doesn’t burn in the oven.
Place an oven rack directly under your broiler and preheat your broiler to the highest setting. Additionally, place a cast iron skillet (you can only use cast iron! do not attempt nonstick or stainless.) on the stovetop burner, turning the heat on high. You want to heat the cast iron skillet for 10 minutes. If it begins to smoke a lot, you can reduce the heat a bit. But you want it HOT.
Place a potholder or thick towel on the handle of the skillet (it will be sooo hot). Carefully slide the pizza into the skillet, dough side down. Don’t worry if a few toppings or pieces of cheese slice onto the surface – it will be totally fine. After about 30 seconds, turn off the burner, grab the skillet and pop it in the oven, right under the broiler. Broil for 1 minute, then using the potholder, grab the handle and rotate 180 degrees, broiling for only 1 more minute. Remove immediately and place on the stovetop. Let cool slightly for about 5 minutes, then use a large spatula to remove the pizza. Cover with the tomatoes (I like to sprinkle some salt and pepper on mine) and chopped lettuce, then slice.