01 -
Drop the butter in a wide pan on medium heat and let it melt. Stir in the onions and coat them well. Cook now and then for about 12 to 15 minutes until they turn golden, soft, and fragrant.
02 -
Toss the thyme, salt, and pepper into the onions. Stir it up, turn off the heat, and set them to the side for later.
03 -
Turn the oven to 350°F to warm up. Take the rolls out, keeping them together. Slice them right through the middle to separate the tops from the bottoms. Put the bottoms, cut side up, into an 11x7-inch pan.
04 -
Lay down half of the cheese slices on the rolls. Stack the roast beef next, then spread the cooked onions evenly. Add the rest of the cheese and finally put the tops of the rolls on.
05 -
In a little bowl, mix the melted butter with the onion soup mix. Use a brush to spread this buttery mix across the roll tops.
06 -
Cover the pan with foil but keep it loose so it doesn’t touch the roll tops. Bake for 25 minutes. Take off the foil and pop it back in for 5 more minutes to get a little browning.
07 -
While baking, follow the au jus package to mix it with the water. Once ready, serve with parsley if you want and the au jus on the side for dipping.