Prepare rolls, and bake according to package directions; cool completely.
Slice rolls in half; spread tops and bottoms of rolls with Blue Cheese Spread. Place roast beef on bottoms of rolls; top beef with Caramelized Onions. Cover with tops.
Make Ahead: Rolls, Blue Cheese Spread, and Caramelized Onions can be made a day ahead. Assemble sandwiches no more than 2 hours before serving.