Preheat the oven to 350 degrees.
Add the Steak-Umms to a large cast iron skillet and cook thoroughly.
Remove the Steak-Umms and add the butter and the onions and bell peppers.
Let brown for 1-2 minutes before stirring, then let brown for another 1-2 minutes before stirring again, add the Steak-Umms back into the pan. AddWorcestershire sauce, salt and black pepper into the pan and stir.
Take it off the heat and scoop it into the pasta shells.
Top each shell with Mozzarella Cheese.
Using the same pan add the beef broth, milk and cornstarch and whisk before turning the heat back on.
Add in the rest of the cheddar cheese a little at a time while whisking for 3-5 minutes or until thickened.
Pour about half the sauce around the shells.
Bake in the oven for about 10 minutes to melt the cheese.
Serve with the remaining sauce.