Preheat your oven to 350°F (175°C). This is the ideal temperature for achieving perfectly baked cookies.
In a medium bowl, whisk together the all-purpose flour, baking soda, and fine sea salt. Set this mixture aside; it will help ensure your cookies rise perfectly.
In a large mixing bowl, beat the softened unsalted butter, light brown sugar, and granulated sugar together using an electric mixer. Beat until the mixture is light and fluffy, about 2-3 minutes.
Mix in the instant pistachio pudding mix, followed by the eggs and pure vanilla extract. Continue to mix until everything is well combined.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined. Be careful not to overmix, as this can lead to tough cookies.
Gently fold in the white chocolate chips and the roughly chopped pistachios. The combination of these ingredients is what makes these cookies truly special!
Using a cookie scoop or tablespoon, drop rounded balls of dough onto a parchment-lined cookie sheet, spacing them about 2 inches apart.
Bake in your preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will continue to set as they cool.
Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a cooling rack to cool completely.