In a small bowl combine mozzerella cheese and 1/4 parmesan cheese. Set aside.
Melt margarine in a large skillet over medium heat. Add onions. Cook and stir until the onions are a rich, golden-brown color. Remove onions with a slotted spoon and set aside, leaving dripping in pan.
Add beef to skillet. Cook and stir until evenly browned; 2-3 minutes. Return onions and any juice to skillet. Add flour, brown sugar, cumin, salt, pepper, and beef broth. Cook and stir (scraping bottom of pan) for 5 minutes or until almost all the liquid is absorbed.
Grease a cookie sheet. Separate crescent rolls into 8 triangles. Slightly overlap long sides of 2 triangles together to make one large triangle; press to seal. Repeat until you have 4 large triangles. Place triangles in a row, all pointing the same direction and overlapping, on the cookie sheet. Press to seal. Spoon onion mixture down the center in 1-1/2" wide strip, leaving about 1" at top and bottom. Sprinkle with the cheese mixture. Bring side points of crescent rolls over the filling to create a braid-like appearance. seal ends. Sprinkle with 2 Tbls. parmesan cheese.
Bake for 15-20 minutes or until deep golden brown. Serve hot with sour cream and au jus.