1. Preheat the oven to 350°F.
2. Boil the potato in salted water. Drain and mash with a fork.
3. In a bowl, mix the potato, parsley, thyme, and duck. Season with salt and pepper.
4. Cut each brick sheet in half. Fold the rounded edge over the straight edge to form a rectangle.
5. Place the filling at one end; fold several times, from one edge to the other, until the other end, keeping a triangular shape.
6. Place on a baking sheet lined with parchment paper.
7. Brush the samosas with duck fat using a brush.
8. Bake for 10 minutes.
9. Remove from the oven and serve.