Preheat oven to 375 °F. Line a baking sheet with parchment paper.
Add the pistachios to a food processor, and pulse for about 30 seconds, or until they are ground into a fine powder (some bigger chunks may remain, that's okay).
Transfer the pistachio powder into a large mixing bowl. Add the flour, baking powder, baking soda, sugar and salt. Use your hands or a whisk to combine everything.
Add the cubed butter to the dry ingredients, use your fingers to work the butter into the ingredients until only small, pea-sized pieces remain.
Add the white chocolate chunks, toss to combine.
Add the egg and 1 cup of whipping cream. Mix with a fork until everything comes together, then use your hands to gently knead until it comes together. It might feel dry, but don't add more liquid unless you have to. And don't overwork, otherwise the scones will be tough.
Transfer to a lightly floured surface, and press the dough into a 9" circle. Doesn't have to be perfect, but it should be all the same thickness. Brush with whipping cream, and sprinkle generously with sugar.
Use a bench scraper or knife to cut into 8 triangles (like you'd cut a pizza). And transfer to the baking sheet. Make sure there is space between each scone because they will expand quite a bit.
Bake for 25-30 minutes or until golden brown. Transfer to a wire rack to cool, and enjoy!