Start by getting your butter right – leave it out for about an hour before baking. You want it soft enough that your finger leaves an indent when you press it.
Heat your oven to 350°F (175°C). Line two baking sheets with parchment paper – don’t skip this, as these cookies can stick thanks to the white chocolate.
In a medium bowl, whisk together your flour, baking soda, and salt. I like to use a fork for this – it breaks up any lumps in the baking soda and distributes everything evenly.
In a large bowl (or stand mixer if you have one), beat the softened butter until it’s creamy – about 30 seconds. Add both sugars and beat until the mixture gets lighter in color and feels fluffy, about 2-3 minutes.
Add your eggs one at a time, beating well after each. Scrape down the sides of the bowl – those stubborn butter bits need to mix in too. Beat in the vanilla.
Gradually stir in the flour mixture – I do this in three additions. Mix until you just stop seeing flour streaks.
Fold in the white chocolate chips and pistachios. The dough will be thick, and that’s perfect.
Drop rounded tablespoons of dough onto your prepared sheets, leaving about 2 inches between each. These will spread as they bake.
Bake for 11-13 minutes, rotating the pans halfway through. Here’s what to look for: the edges should be lightly golden brown, but the centers will look slightly underbaked and puffy. They’ll sink down and set up as they cool.
Let them cool on the baking sheets for 5 minutes – they’re too soft to move right away. Then transfer to a wire rack to cool completely.