Preheat the oven to 350°F (175°C) and line a baking sheet with parchment or lightly grease it. On a lightly floured surface, roll the French bread dough into a 12×18-inch rectangle. Spread ketchup and mustard evenly over the dough, leaving a small border around the edges.
In a skillet over medium heat, cook the ground beef with diced onion until browned. Season with salt and pepper, drain excess fat, then layer the beef over the prepared dough. Sprinkle crumbled bacon and chopped pickles on top, and place the American cheese slices evenly over the filling.
Carefully roll the dough from one long edge to the other, tucking and sealing the edges. Place the seam side down on the baking sheet, brush with beaten egg, and sprinkle sesame seeds on top. Bake for 20–25 minutes until the bread is golden brown.
Allow the baked bread to rest for 5 minutes before slicing. Serve warm with Thousand Island dressing for dipping, creating a fun, shareable meal inspired by classic cheeseburgers.
