Preheat oven to 180C (350F). Line baking trays with baking parchment.
Wash your hands thoroughly.
Place chicken, carrot, spring onion, bread crumbs, lemon, thyme and salt and pepper to taste in a large mixing bowl, add egg and combine well with your hands, smooshing it all together thoroughly.
Cut each of the pastry sheets in half, place sausage meat along the length of the middle of each sheet and roll up, sealing the edges with a brush of egg wash.
Place the long rolls on prepared baking trays, cut each roll to small bite-sized pieces, brush the tops with egg wash and sprinkle with the nigella seeds.
Bake for 20-25 minutes, or until golden brown.