Place butter in a medium saucepan over medium-low heat and melt completely

Continue cooking the butter, swirling occasionally, until it foams and then turns amber in color with a nutty aroma (about 5-6 minutes)

Remove from heat immediately and transfer to a heat-safe bowl to cool for 20-30 minutes (the butter should still be liquid but not hot)

While the butter cools, preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper

In the bowl of a stand mixer fitted with the paddle attachment, combine the cooled browned butter with both sugars

Mix on medium speed for 1 minute until well combined (it won't be fluffy since the butter is liquid)

Add the honey, egg, vanilla extract, sea salt, and baking soda to the mixture

Beat for another minute until all ingredients are thoroughly incorporated

Reduce mixer speed to low and gradually add the flour, mixing just until no dry streaks remain

Using a spatula, fold in the chopped pistachios and white chocolate chips until evenly distributed

Using a medium cookie scoop (about 2 tablespoons), portion the dough onto the prepared baking sheets, spacing cookies about 2 inches apart

Bake one sheet at a time in the center of the oven for 8-9 minutes, or until the edges are just turning golden while the centers still look slightly underdone

Remove from oven and immediately sprinkle with flaked sea salt if desired