1. Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.

2. Heat butter or oil in a skillet over medium heat. Add onion and sauté until soft, about 3–4 minutes.

3. Add garlic and cook for 30 seconds. Stir in mushrooms and cook until moisture is evaporated and mushrooms are golden, about 8–10 minutes.

4. Season with salt, pepper, and herbs. Let the mixture cool slightly.

5. Unfold puff pastry sheets on a lightly floured surface. Gently roll to even out.

6. Spread mushroom mixture evenly, leaving a small border on one long edge.

7. Sprinkle cheese over the mushrooms.

8. Roll the pastry tightly from the filled edge. Seal the roll with the clean edge.

9. Slice into 1/2 to 3/4 inch rounds. Arrange on the prepared baking sheet.

10. Brush tops with beaten egg.

11. Bake for 18–22 minutes or until golden and puffed.

12. Cool slightly before serving.