Preheat the oven to 356°F.
Chop the pistachios.
Roll out one sheet of puff pastry on a sheet of parchment paper.
Spread the pastry with raspberry jam, leaving a 2-centimeter border.
Sprinkle with chopped pistachios.
Moisten the border with a little water using a pastry brush, then cover with the second sheet of puff pastry.
Seal the edges by pressing firmly around the border.
Brush the top with the egg, beaten with a little water.
Place an upside-down glass or a round cookie cutter in the center of the tart.
Cut about twenty strips around the glass from the center to the edge.
Remove the glass and twist each strip 4 to 5 times to form spirals.
Bake for 30 minutes.
Let cool on a wire rack and serve decorated with fresh raspberries.