Preheat the oven to 375°F (190°C).
Using the butter, grease twelve 3-inch (8-cm) muffin tins.
Roll the dough out thinly on a lightly floured board and use it to line the muffin tins.
Prick the bottoms with a fork and bake for 10 to 12 minutes or until the pastry is crisp and golden.
Remove the tins from the oven, let the pastry cool thoroughly and then turn the tarts out of the tins.
Spoon about 2 teaspoonfuls of the lemon curd into each tart.
Fill a pastry tube fitted with a star nozzle with the cream and squeeze it over the lemon curd to cover it completely.
Sprinkle over the pistachio nuts, if you are using them, and serve.