Preheat oven to 350° F.

Line an 8x8 light colored metal baking pan with parchment paper and set aside.

Melt butter in a medium sauce pan on medium heat. Stir the butter to make sure it melts evenly. Once the butter is completely melted, it will start to foam up. Continue stirring the butter. As it cooks, it will start to change into a deeper color. This could take 6-8 minutes. You'll start to notice a nutty aroma and the butter will begin to have brown specs at the bottom of the pan. The entire process of browning butter from start to finish should not take more than 10 minutes on medium heat.

Once butter is browned, pour it into a heat proof bowl and set it aside to cool for about 5 or 10 minutes.

Mix the batter: In a medium bowl, add cooled brown butter and sugar and mix using a spatula until combined. Add the egg, yolk, and vanilla and mix until combined. Then add the pistachio cream directly into the batter and mix. Add the salt and flour and mix until incorporated. Lastly, add the chocolates and pistachio pieces and mix until just combined.

Bake the Blondies: Pour the batter into the prepared baking pan and spread it out, then add dollops of pistachio cream and spread it out with a knife, or just drizzle it on top. Then top with some extra chocolate and pistachio pieces, and bake for 20-25 minutes. You'll see the sides get a little light brown and the middle will have puffed up some. Don't over bake.

Remove from oven and allow to cool before slicing.