Heat oven to 350°F. Spray large cookie sheet with Crisco® Original No-Stick Cooking Spray. Place both loaves of dough, seam sides down and 3 inches apart, on large cookie sheet. Using sharp knife, cut 4 or 5 diagonal slashes (1/2 inch deep) on top of each loaf. Bake 22 to 26 minutes or until golden brown.
Meanwhile, in 12-inch skillet, heat oil and butter over medium heat. Add onion; cook 15 to 18 minutes, stirring occasionally, until tender. Stir in broth and beef; cook 4 minutes. Remove from heat.
In small bowl, mix mayonnaise, chipotle chiles, lime juice and pepper.
When bread is done baking, set oven control to broil. Cut each loaf in half horizontally, cutting to but not completely through one long side; place cut sides up on cookie sheet. Spread 1/2 cup mayonnaise mixture over cut sides of each loaf. Using slotted spoon, remove beef and onion from broth mixture, reserving broth mixture. Top each loaf with half of the beef and onion; top with cheese.
Broil with tops 6 inches from heat 2 to 3 minutes or until bread is lightly toasted. Cut each sandwich into 3 pieces. If desired, skim fat from broth mixture and serve broth with sandwiches for dipping.