Preheat the oven to 400°F (200°C) and line a baking tray with parchment paper.
In a mixing bowl, combine the sausage, onion, garlic, bread crumbs, herbs, salt, and pepper. Mix well with your hands until fully blended.
On a lightly floured surface, roll out the puff pastry if needed. Place the sausage mixture down the center, shaping it into a long log.
Brush the edges with beaten egg. Fold the pastry over the filling, sealing tightly. Place seam-side down on the baking tray.
Brush the top with more egg. Optionally, decorate with pastry cutouts.
Bake for 25–30 minutes or until golden and puffed. Let rest for 5 minutes before slicing and serving.
