Step 1: Brown the butter. In a medium saucepan over medium heat, melt the butter. Continue to cook, stirring frequently, until it turns a golden brown color and develops a nutty aroma, about 5-7 minutes. Be careful not to burn it!
Step 2: Cool slightly. Remove the saucepan from heat and let the brown butter cool slightly while you prepare the other ingredients.
Step 3: Prepare the cookie dough. In a large mixing bowl, combine the brown sugar and granulated sugar. Add the cooled brown butter and mix until well combined.
Step 4: Add eggs and vanilla. Beat in the eggs, one at a time, followed by the vanilla extract, until the mixture is smooth and creamy.
Step 5: Combine dry ingredients. In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.
Step 6: Incorporate dry into wet. Gradually add the dry ingredients to the wet mixture, stirring until just combined. Avoid overmixing.
Step 7: Fold in mix-ins. Gently fold in the chocolate chips and chopped Dubai pistachios until evenly distributed throughout the dough.
Step 8: Prepare the baking pan. Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal.
Step 9: Spread the dough. Pour the cookie dough into the prepared baking pan and spread it evenly.
Step 10: Bake. Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and the center is set. A toothpick inserted into the center should come out clean or with a few moist crumbs.
Step 11: Cool completely. Allow the cookie bars to cool in the pan for about 10 minutes, then lift them out using the parchment paper and transfer to a wire rack to cool completely.
Step 12: Slice into bars. Once cooled, slice into squares or rectangles and serve.