In a small saucepan, combine the cranberry sauce, vinegar, red onion, and 1/4 cup of water over medium heat. Season with salt and pepper and cook until onions are tender and sauce has slightly reduced. Take off heat then set aside to cool.

Preheat the oven to 180?C.

Lay the pastry on a tray lined with baking paper. Cut the edges of the square pastry to make a rough circle then mark a circle with a smaller plate or bowl to make an inner circle. Make 4 cuts in the inner circle.

Spread the cranberry onion jam around the outer circle leaving a 1-2cm border around the outside, then arrange the slices of brie and rosemary sprigs on top.

Take one point of the centre star over the filling and bring the outer edge of pastry inwards. Press the two together and continue until you have formed a wreath.

Brush the tops of the wreath with beaten egg then place in the oven for 15-20 minutes or until puffed and golden brown.