This copy cat Arby’s Beef ‘N Cheddar recipe is so good! Arby’s is so underrated. 1 pound Thinly sliced roast beef with au jus4 onion buns1 can cheddar sauceArby’s saucePlace au jus in a sauce pan over high heat. Add beef and allow to come to a boil then cut the heat. Heat up cheddar sauce and toast the onion buns in a non stick skillet. To build the sandwich place your toasted bun then your roast beef. Spoon the cheddar sauce on top and drizzle the Arby sauce if preferred then add the bun on top