Remove puff pastry from the refrigerator and let it sit at room temperature for 15–20 minutes so it’s pliable but still cold. Preheat the oven to 200°C (400°F). Line a baking sheet with parchment paper and lightly dust your work surface with the all-purpose flour.

Roll and cut

On the floured surface, unfold each puff pastry sheet and roll lightly with a rolling pin to even thickness (about 1/8 inch). For individual pastries: cut each sheet into 6 rectangles (about 10 x 7 cm / 4 x 3 inches). For two long loaves: cut each sheet into 2 long rectangles. Adjust sizes to match the amount of filling.

Egg wash

In a small bowl, whisk together the egg and 1 tablespoon water until smooth. Reserve for brushing the assembled pastries.

Assemble pastries

Place about 2–3 tablespoons of cooled sausage filling down the center of each rectangle (or form a 1–1.5 inch thick line for long loaves). Fold the pastry over the filling to form a pocket or roll and seal the edges by pressing with a fork or crimping with your fingers. Transfer assembled pastries to the prepared baking sheet, spacing 1–2 inches apart. Brush each pastry generously with egg wash and sprinkle with sesame or poppy seeds if using. If making larger loaves, cut a couple of small slits on top to vent.

Bake

Bake in the preheated oven for 18–25 minutes for individual pastries, or 25–35 minutes for larger loaves, until the pastry is puffed and deep golden brown. Rotate the sheet halfway through baking for even color. Remove from oven and let cool on the sheet for 5 minutes before transferring to a wire rack.

Sausage filling

Soak crumbs

Place bread crumbs in a small bowl and pour the milk over them. Let sit 3–5 minutes until absorbed; the mixture should be moist but not soupy.

Cook onions and garlic

Meanwhile, thinly slice the yellow onion. Heat olive oil and butter in a large skillet over medium heat. Add the sliced onion and a pinch of salt and cook, stirring occasionally, until softened and starting to brown, about 8–10 minutes. Add the minced garlic and fresh thyme and cook another 1 minute until fragrant. Remove from heat and let cool 3–5 minutes.

Combine filling

In a large bowl, add the sausage meat (remove casings if present). Add the cooled onion mixture, soaked bread crumbs, Dijon mustard, Worcestershire sauce, chopped parsley (if using), salt and black pepper. Mix gently with your hands or a spoon until just combined — avoid overworking to keep the filling tender. Taste a small pinch by cooking it in a skillet (optional) and adjust seasoning if needed.

Portion and cool

Form the mixture into small logs or balls matching the size of your pastry rectangles (about 2–3 tablespoons each). Place formed portions on a plate or tray and chill in the refrigerator for 10–15 minutes to firm up; this prevents the filling from leaking while baking.