Process the pistachios in a food processor until Finley chopped. Do not over process, or it will become oily.
Add the flour, baking powder and sugar and pulse about 5 time to fully incorporate.
Add the cut butter and pulse until the butter is not noticeable and the mixture is slightly coarse. About 8-10 seonds.
Add the egg, vanilla extract and heavy cream and process until a moist, playable dough is formed.
Mount the dough onto a clean work surface and press it together with your hands.
Divide the dough into two and wrap each part with plastic wrap shaping it into a 6-inch disk.
Refrigerate for at least one hour and up to three days.