Preheat oven to 350°F
Saute onions in oil until translucent. Set aside.
Brown ground beef chuck, drain and return to pan. Add butter, onion powder, garlic powder, pepper, salt and worcestershire sauce. Cook until butter melts and spices are incorporated. Add cooked onions and turn off heat.
Place bottoms of rolls into a large casserole dish. Generously smear with yellow mustard.
Top each with a scoop of prepared ground beef chuck, half a slice of cheese (or more!), 3-4 pickle slices and tops of rolls.
Cover dish with foil and bake 15-20 minutes or until melty.
Serve with fries and sweet tea!