Preheat your oven to 400F
In a large mixing bowl combine the peppers, sausage, onion, garlic, oil and Italian Seasoning. Toss vigorously to evenly coat everything with the oil and spices.
Evenly spread the sausage and peppers into a large baking dish and roast for 1 hour at 400F.
When the peppers and sausage are done, remove from the oven and turn on the broiler. Add the marinara sauce to the baking dish and fold it in with a large spoon.
Cut open the buns and place them on a metal baking tray, butter both sides. Add sausages and peppers to one side of each bun and top with both cheeses. Broil for 60-90 seconds on high til the mozzarella is loose and gooey
Remove the sandwiches from the oven, add fresh basil, cut in half and serve