1) Preheat oven to 200 degrees C/Gas Mark 6.
2) In a food processor, puree the lobster meat with the salt and paprika.
3) With the motor running, add the cream in a steady stream and blend until the mixture is smooth, then add the tarragon.
4) Place the pastry shells on a lightly greased baking tray, brush the tops with the egg wash, being careful not to let the wash drip down the sides, and bake in the middle of the preheated oven until they are just beginning to color, about 7 minutes. Transfer the shells to a rack and let them cool completely.
5) Pipe or spoon the lobster mousse into the puff pastry shells and bake in the oven until the mousse is set and the shells are golden brown, about 4 to 5 minutes.
6) Serve immediately topped with a slices of lobster and a dollop of caviar, if using.