01 -
Set your oven to 350°F. Line a 9x13 pan with parchment and butter it.
02 -
Cut through all the rolls in one go, keeping them attached. Place the bottom half into your prepared pan.
03 -
Start layering: half the cheese, roast beef, fried onions (if using), the rest of the cheese, and then the top layer of rolls.
04 -
Stir together melted butter, a tablespoon of the au jus mix, and the remaining topping ingredients, then brush this mixture over the rolls.
05 -
Leave uncovered and cook for 15-20 minutes. You'll know it's ready when the cheese is gooey, and the rolls are golden on top.
06 -
Follow the package steps to heat up the leftover au jus mix with water, cooking till it's a bit thickened.