Beat butter and sugars in standing mixer for about 2 minutes, until light and fluffy.  Beat in eggs, one at a time, then beat in zest and vanilla extract.

In a separate bowl, whisk together flour, baking powder and baking soda.  With mixer speed on low, gradually add to butter mixture and beat until well combined.  Stir in all but 3 tbsp of the pistachios, and the white chocolate.  Cover mixer bowl and refrigerate dough 30 minutes (or up to 48 hours).

Preheat oven to 375ºF. Line baking sheets with parchment paper. Scoop dough by tablespoonfuls and roll between palms to make perfect balls.  Arrange 2" apart on prepared baking sheets, sprinkle with remaining pistachios and a pinch of sea salt,  and bake 6-8 minutes, until golden at edges and slightly underdone.  Cool a few minutes on baking sheet before transferring to wire racks to cool completely.