Lay a sheet of baking paper on a baking tray. Put one of the squares of puff pastry on top of this.
Spread the pesto over the square of pastry. Cut the halloumi into small pieces and sprinkle over the top, followed by the mini peppers. Top with the other square of pastry and press down gently.
Put a glass in the middle of the square and gently score around it with a knife (gently - don’t cut all the way through) to make a circle. From this circle, cut lines out to the edges of the pastry, through all layers.
Twist each line of pastry into a small spiral, so that you end up with a snowflake shape.
Beat the egg in a bowl and brush over the pastry. Put in the oven and bake for 20-25 minutes until risen and golden.