Brown the Italian sausage in a cast iron skillet and set aside on a plate once browned. Drain off most of the drippings.
Saute the chopped green pepper and chopped onion in the skillet. Add the frozen corn (no need to thaw), and the undrained can of diced tomatoes. Let simmer for about 10 minutes.
Add the browned sausage in with the veggies and stir in the Italian seasonings. Sprinkle the mozzarella cheese and Parmesan cheese of the sausage and veggies.
In a mixing bowl, whisk together the milk, oil, egg, flour and salt. Pour over top the cheese. (What I did not do, but what you could do at this point is sprinkle some yellow cornmeal over the batter. Give it that extra pizza taste.)
Bake at 400 for 15-20 minutes, or until begins to turn golden on top.
Serve Upside Down Cast Iron Skillet Pizza, as is...or with a side of carrot sticks or sliced fruit.