Put all the ingredients for the pesto in a high speed blender and process until smooth. Taste and add salt to taste, if required.

Preheat the oven to 180C (350F) and position a shelf in the centre.
Place your bottom sheet of puff pastry on a piece of baking paper (or the paper it came rolled in).

Spread the pesto in an even layer, leaving a small border around the edge.
Drape the second puff pastry sheet over a rolling pin and position it over the bottom sheet. Press the edges lightly to seal.

Position a ramekin in the centre. Use a sharp knife to cut the pastry into quarters and then cut each quarter in half and so on until you have divided your tart into 24 pieces (or just an equal number of pieces).

Twist the pastry pieces, in pairs, inwards twice and then seal at the ends.
Brush the puff pastry snowflake with egg wash and sprinkle with a little grated cheese.
Bake for 25-30 minutes until golden and fragrant

Transfer your snowflake onto a large platter and serve with a platter of prosciutto slices so that everyone can help themselves.

Notes
Serve leftover pesto with pasta, spread over crostini, or use it to flavour soups.