### Instructions
1. **Preheat Oven & Prepare Pastry:** Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper. Unroll the thawed puff pastry sheet onto a lightly floured surface. Using a sharp knife or pizza cutter, cut the pastry into 12-16 equal squares (e.g., 2-inch squares).
2. **Add Filling:** Place a small amount (about 1 teaspoon) of your chosen filling in the center of each pastry square. Be careful not to overfill.
3. **Form Parcels:** Bring two opposite corners of each pastry square together over the filling and press firmly to seal, forming a triangle. Alternatively, you can bring all four corners to the center and pinch them together to form a small purse. Ensure the edges are well-sealed to prevent filling from escaping.
4. **Egg Wash:** Arrange the parcels on the prepared baking sheet. Lightly brush the tops of each parcel with the beaten egg wash. This will give them a beautiful golden sheen when baked.
5. **Bake:** Bake for 12-15 minutes, or until the pastry is puffed and golden brown. Baking time may vary slightly depending on your oven and the size of your parcels.
6. **Cool & Serve:** Remove the parcels from the oven and let them cool on the baking sheet for a few minutes before transferring to a wire rack. Serve warm or at room temperature.
### Short Tips
* **Don’t overwork the pastry:** Handle puff pastry as little as possible to maintain its flakiness.
* **Chill if soft:** If your puff pastry becomes too soft during preparation, pop it back in the fridge for 5-10 minutes.
* **Vary the shapes:** You can also fold them into rectangles, or even use small cookie cutters for fun shapes before filling.
* **Make ahead:** Assemble the parcels, egg wash them, and then refrigerate for up to an hour before baking. You can also freeze unbaked parcels on a baking sheet until solid, then transfer to a freezer bag and bake from frozen (add a few minutes to the baking time).
* **Get creative with fillings!** The possibilities are endless. Consider spinach and feta, mushroom and goat cheese, apple pie filling, or even Nutella for sweet variations.
