Preheat oven to 350 degrees F. Roast eye of the round to a little less than desired doneness if cooking roast in advance of making sandwiches. If making sandwiches right away, cook to desired doneness. Thinly slice beef.

In a large skillet saute onions in butter until translucent over medium heat. Add meat and heat through. In skillet, separate meat and onions into portions for sandwiches. Lower heat and place 2 slices of provolone on sandwiches portions and heat until cheese begins to melt. Using a spatula remove sandwich portions to split hoagie rolls. Repeat with other portions and serve sandwiches immediately.