Preheat the oven to 450° F.
Cook steak fries according to package directions.
While fries are cooking, melt the butter in a large skillet over medium-high heat.
Add onions and cook until the onions are browned and tender (approximately 15-20 minutes).
In a medium bowl, mix together beef broth and flour. Pour over cooked onions, add the salt, and stir until mixture comes to a boil. Set aside.
Lower oven heat to 400° F.
Place cooked fries in an oven-safe skillet.
Top steak fries with onion mixture, provolone cheese, and gruyere cheese.
Bake for 10 to 15 minutes or until cheese is melted.
Top with parsley, for garnish.