Preheat Oven:
Preheat your oven to 350°F (175°C) and grease an 8×8-inch baking dish or line it with parchment paper for easier removal.
Mix Wet Ingredients:
In a large bowl, cream together the room temperature butter, brown sugar, and granulated sugar until the mixture is light and smooth, about 3-4 minutes. Beat in the eggs one at a time, then add the vanilla extract and pistachio pudding mix, mixing until well combined.
Combine Dry Ingredients:
In a separate small bowl, sift together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Add Mix-ins:
Fold in the roughly chopped pistachios and white chocolate chips until evenly distributed throughout the batter.
Bake the Blondies:
Transfer the batter to the prepared 8×8-inch baking dish, spreading it out evenly. Bake in the preheated oven for 25-28 minutes, or until the blondies are golden brown and a toothpick inserted into the center comes out clean or with just a few moist crumbs.
Cool and Serve:
Allow the blondies to cool in the baking dish for at least 30 minutes before cutting them into squares. This will help them set and make them easier to slice.
