Egg and sausage tart

Roll out a 20cm x 20cm square of ready-made puff pastry. Lay it on a greased baking tray. Prick the centre with a fork, score a 2cm border around the edge and brush the border with 1 large beaten egg. Chill in the refrigerator for 20 minutes. Preheat the oven to 200°C. In a bowl, combine 100g créme fraîche and 60g shredded Gruyère and season to taste. Spread this mix on the pastry, keeping the border clean. Lay 4 cooked sausages around the edges of the tart. Bake until golden and risen, about 15 minutes. Remove from the oven and crack 1 large egg onto the tart. Continue baking until the egg is cooked, about 7 minutes. Serve garnished with chopped fresh flat-leaf parsley.