Prepare the Puff Pastry: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper. While the oven is heating, roll out the thawed puff pastry on a floured surface until it’s about ¼ inch thick, ensuring it fits your baking sheet when rolled out.
Assemble the Filling: Spread 1 teaspoon of Dijon mustard evenly over the rolled-out pastry. Begin layering the filling by adding 1 cup of thinly sliced turkey bacon, followed by 1 cup of well-drained sauerkraut, and then sprinkle 1 cup of shredded Swiss cheese over the top.
Roll and Slice: Starting from one side, tightly roll the pastry into a log, making sure to seal the seam by pinching it together. Once rolled, slice the log into 1-inch pieces to create your rolls.
Add Finishing Touches: Place the sliced rolls on the prepared baking sheet. Brush each roll with the beaten egg to create a golden crust. If desired, sprinkle ½ teaspoon of dried thyme or caraway seeds for an added flavor boost, then top with the remaining ½ cup Swiss cheese.
Bake: Place the baking sheet in the oven and bake the rolls for 20-25 minutes, or until they turn golden brown and crispy. For best results, allow them to cool slightly before serving to let the cheese set a bit.