Preheat the oven to 275°F. Line a cookie sheet with parchment paper and set aside.
In a medium bowl, whisk together the flour, dry pistachio pudding mix, baking soda, and salt until evenly blended. Set aside.
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together until light and fluffy, about 2–3 minutes. Scrape down the sides of the bowl as needed.
Add the eggs and butter vanilla emulsion, and mix until fully incorporated.
Gradually add the flour mixture to the wet ingredients, mixing on low speed just until combined. Do not overmix.
Using a spatula, gently fold in the chopped pistachios and white chocolate chips until evenly distributed throughout the dough.
Scoop the dough into 2-tablespoon portions and place them about 2 inches apart on the prepared baking sheets.
Bake for approximately 25 minutes, or until the cookies are set but still pale in color.
Slide the parchment from the baking sheet and allow to set for 5–10 minutes before transferring to a wire rack to cool completely. They will continue to firm up slightly as they cool while remaining soft inside.