Step 1: Preheat the Oven
1. Preheat Oven: Preheat your oven to 375°F (190°C).

Step 2: Prepare the Brie
1. Remove Packaging: Unwrap the brie cheese and place it on a baking sheet lined with parchment paper.
2. Top with Preserves: Spoon the plum preserves over the top of the brie. If using, sprinkle the chopped rosemary or thyme and nuts on top for added flavor and texture.

Step 3: Wrap the Brie
1. Prepare Puff Pastry: Roll out the puff pastry on a lightly floured surface. Cut it into a square large enough to wrap around the brie completely.
2. Wrap the Brie: Place the brie in the center of the puff pastry square. Fold the pastry over the cheese, pinching the edges to seal. You can trim any excess pastry if needed.

Step 4: Egg Wash
1. Apply Egg Wash: Beat the egg in a small bowl and brush it over the top of the wrapped brie to give it a golden color when baked.

Step 5: Bake
1. Bake in Oven: Place the baking sheet in the preheated oven and bake for 20-25 minutes, or until the pastry is golden brown and puffed.

Step 6: Serve
1. Cool Slightly: Remove from the oven and let it cool for a few minutes before serving.
2. Enjoy: Serve warm with crackers, sliced baguette, or fresh fruit for dipping.