In a small sauce over medium heat, add butter and bring to a boil. Continue heating over medium heat, constantly stirring until the butter has turned a nutty brown color. It may be hard to see the color if your butter is foaming a lot, so periodically take it off the heat to check the color. Remove from heat, place into a heat proof glass and then into the freezer to cool off for 15-30 minutes. When ready, the butter should still be liquid and just barely warm to the touch.

Preheat oven to 325°F, and prepare a 9” square baking pan with parchment and cooking spray. Next, in a medium mixing bowl, add flour, baking soda, and salt. Whisk together to combine, then set aside.

Add cooled brown butter, white sugar, and brown sugar to a stand mixer fitted with the paddle attachment. Beat on medium until well-combined and smooth.

Add in vanilla, eggs, and egg yolk, and turn the stand mixer on medium. Mix until well-combined, then turn the stand mixer to high and beat for another 3 minutes, or until the batter looks light and fluffy.

Add in the dry mixture and mix on low until combined, scraping at the edges. Ensure it is well combined, but do not overmix. Add in the white chocolate chips and pistachios, and fold with a spatula until well dispersed.

Place batter into baking pan, spread it out evenly, then place into the oven to bake for 30-35 minutes. When ready, the White Chocolate Pistachio Blondies should start browning on the edges. Let cool completely before drizzling with chocolate.

Add chopped white chocolate to a medium-sized pyrex measuring cup. Place into the microwave to melt for 1 minute. Remove from microwave and stir. If the chocolate isn’t fully melted, place back into the microwave in 15 second intervals, stirring in-between, until the chocolate has melted.