Brown ground beef with onion, salt and pepper (more or less to taste) until pink is gone. Drain fat/liquid. Add about 1/2 cup of beef gravy (just use enough to moisten ground beef) and simmer for 20 minutes. Cool completely. Roll out one can of crescent roll dough in one large rectangle, sealing all seams. Top with 1/2 of ground beef mixture and 1/2 cup cheddar cheese. Roll from long end to form log and slice into about 10 sections. Repeat with 2nd can of dough. Arrange onto greased baking pan and bake in a 375 degree oven for 15-20 minutes until golden brown. Serve topped with additional gravy if desired.