Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

In a medium bowl, whisk together the all-purpose flour, baking soda, and salt.

In a large bowl, beat the softened unsalted butter, granulated sugar, and light brown sugar until light and creamy, about 2 minutes.

Add the instant pistachio pudding mix to the butter mixture and beat until well combined. Incorporate the eggs one at a time, and mix in the vanilla extract.

Gradually add the dry mixture to the wet ingredients, mixing just until combined. The dough should be soft and slightly sticky.

Gently fold in the white chocolate chips and chopped shelled pistachios.

Using a cookie scoop, portion about 1.5 tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart.

Bake for 9 to 11 minutes, or until the edges are set while the centers appear slightly underbaked.

Allow the cookies to rest on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.