Unroll 8 of the crescents on a standard cookie sheet. Flatten each crescent to stretch it farther.
Cover each crescent with a slice of roast beef. Then place a slice of Swiss cheese over the roast beef.
Roll the crescents starting from the wide end and ending at the narrow end, pressing down on the narrow end so the roll stays together.
Bake at 375 degrees for 11 – 13 minutes, or until the crescents are a golden color. Repeat with the other 8 crescent rolls or save them for another meal. Serve with hot Au Jus.