Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish.
Layer the Dough: Unroll one can of crescent roll dough and press it into the bottom of the prepared baking dish, sealing the seams to form a crust.
Layer the Meats and Cheeses: Layer the ham, salami, pepperoni, provolone, and mozzarella evenly over the dough.
Add Veggies: Sprinkle the chopped roasted red peppers, banana peppers, and black olives over the layers of meat and cheese, if using.
Top with More Dough: Unroll the second can of crescent roll dough and place it over the top, carefully sealing the seams and pressing to cover the filling.
Add Egg Wash and Seasoning: Brush the beaten eggs evenly over the top layer of dough. Sprinkle with Italian seasoning and grated Parmesan cheese.
Bake: Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and the dough is cooked through.
Cool and Slice: Allow the Italian sub squares to cool for about 5-10 minutes before slicing into squares.