2 spring onions or 1/2 small red onion, finely sliced
1/2 teaspoon dried thyme (optional)
salad leaves, to serve
Cut the puff pastry in half to form 2 rectangles and place these on a baking sheet. Spread the mustard over the bases, leaving a 1 cm (1/2 inch) border, and top with the sliced Brie. Brush the border with the beaten egg or milk.
Scatter over the spring onion and thyme, if using, and bake in a preheated oven, 200˚C (400˚F), Gas Mark 6, for 12–15 minutes until crisp and golden.