Preheat oven to 350 degrees.
Heat olive oil and 1 tablespoon butter in a large skillet over medium heat.
Add onions and saute, stirring occasionally reducing temperature slightly if needed to avoid burning until onions are soft and tender, about 15 minutes.
Add a dash of balsamic vinegar and pinch of salt. Increase heat to medium high and cook for an additional minute or so until fragrant and balsamic is absorbed into onions.
Remove onions from skillet.
While onions are cooking, mix garlic powder with melted butter. Brush onto inside of hoagie rolls. Bake in oven for 5-7 minutes until toasted. Remove from oven and set aside.
Add shaved steak to skillet, pulling steak apart (you don't want clumps). Cook over medium to medium high heat, stirring and turning occasionally until meat is cooked throughly.
Heat up Cheez Whiz in microwave, removing top and following heating instructions on jar.
To assemble, place a generous amount of shaved steak on toasted hoagie roll, top with melted cheese, onions and a pinch of salt.