Portabella Mushroom ' Cheesesteak '

Makes 4 sandwiches
2 large portabella mushrooms (4-5 small)
1-2 large onions
butter
extra virgin olive oil
4 hoagie rolls (sub)
mozzarella cheese
parmesan cheese
ketchup

Wash portabellos with a damp paper towel.
The portabellos might seem a little dry, especially around the'gills'.
Cut them into strips and place on a dinner plate.
Cover mushroom strips with olive oil and allow them to soak while you prepare the onions.
If they still appear dry, add more oil.
Cut onions into thin strips.
Caramelize onions over medium or medium high heat in butter and olive oil, stirring frequently until golden brown.
The amount of oil and butter depend on the moisture content of your onions, I usually use more butter than olive oil.
The longer and slower you cook the onions, the better.
You can do this from 15-45 minutes depending on your schedule.
Nothing tastes better than a nicely caramelized onion!
Once onions are done, remove from skillet.
Preheat broiler.
Use the same skillet to heat up the portabello mushrooms.
Again, cook in butter and olive oil just until warm and tender.
(I recommend not cooking the mushrooms and onions together, portabellos have a habit of turning other food black.) Slice open the sandwich rolls and remove a little of the bread stuffing from each side.
Distribute cooked portabellos evenly to each roll.
Cover with caramelized onions.
Add mozzarella cheese to taste.
Sprinkle with parmesan cheese.
Broil until cheese melts and rolls begin to brown, 3-5 minutes.