In a large bowl, gently mix together the raspberries with the cornstarch, the sugar minus 1 tablespoon (reserve this to sprinkle on top of the pie), the cinnamon, the vanilla extract, and the lemon juice.
Using a 9-inch pie dish, place the rolled shortcrust pasty into the dish, and then carefully cut off the excess pastry around the edges.
Ladle the raspberry mixture into the pie dish on top of the pastry base.
Use the second section of shortcrust pastry to top the pie. To create a lattice pattern, use a sharp knife or a pizza cutter to cut thin strips of pastry, then alternate placing these gently on top of the pie. Trim the edges.
Brush the top of the pastry with the beaten egg and then sprinkle the reserved tablespoon of sugar on top of the pie.
Place the pie into the oven and bake for 40 minutes, then take it out and cool for 20 minutes before serving.
Optionally serve with whipped cream or vanilla ice cream.