Mix garlic, Parmesan, olive oil, parsley, Italian seasoning, salt, pepper, and red pepper flakes together to form a paste.
Slice flank steak horizontally through the middle without cutting all the way to the other side. Open the 2 sides and spread them out like an open book.
Rub both sides of steak with the seasoning paste. Arrange provolone cheese over steak, leaving a 1-inch border. Top with roasted red peppers. Roll up steak and tie at 1-inch intervals using kitchen twine. Refrigerate 2 hours or up to overnight.
Preheat the oven to 400 degrees F (200 degrees C). Grease a baking dish and place steak inside.
Roast in the preheated oven until internal temperature reaches 145 degrees F (65 degrees C), about 1 hour.
Remove from oven and let rest 5 to 10 minutes before cutting into 1-inch slices. Be sure to remove the twine before serving!
