Start by placing your unsalted butter in a medium saucepan over medium heat. Keep stirring as it melts and begins to foam. Cook until it turns a golden hue, about 6 to 8 minutes.

Remove the butter from heat and pour it into a heat-safe bowl. Let it cool for about 5 to 10 minutes.

In another mixing bowl, whisk together the warm brown butter and brown sugar until smooth.

Add in the egg, egg yolk, and vanilla extract, mixing until well incorporated.

Stir in the pistachio cream, blending into the batter evenly.

Gently fold in the flour and salt, being careful not to overmix.

Folding in the chocolate chips and chopped pistachios.

Preheat the oven to 350°F (175°C) and prepare an 8×8-inch baking pan by lining it with parchment paper or lightly greasing it.

Spread the blondie batter evenly into the prepared pan and swirl with extra pistachio cream. Optionally sprinkle additional chocolate chips and pistachios on top.

Bake for 20 to 25 minutes, until the edges are golden and the center remains soft.

Let the blondies cool completely in the pan before slicing into squares.