Preheat oven to 400°F. Line a baking sheet with parchment paper.
Heat olive oil in a saucepan over medium heat. Add shallot, and saute for 2 minutes or until translucent. Whisk in cornstarch.
Add beef broth, a little bit at a time, whisking constantly. Add beef consommé and black pepper. Bring to a boil, then reduce heat to low to keep warm.
Slice baguette into quarters, then slice in half lengthwise to create sandwiches.
Place sandwich bottoms on prepared baking sheet. Top with brisket, then cheese. Place sandwich tops next to them to toast. Bake for 10-12 minutes or until fully heated and cheese is melted.
Serve sandwiches with prepared au jus for dipping.