Preheat your oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper.

Melt ½ cup of unsalted butter in a medium saucepan over low heat.

In a large mixing bowl, combine melted butter and 1 cup of light brown sugar until smooth. Add 2 eggs and 1 teaspoon of vanilla extract, mix until incorporated.

Sift in 1½ cups of all-purpose flour and a pinch of salt into the wet mixture. Fold until just combined.

Pour the blondie batter into the prepared pan, spreading it evenly.

In a separate bowl, beat 8 ounces of cream cheese and ½ cup of granulated sugar until smooth. Add 1 egg yolk and 1 teaspoon of vanilla extract, mixing until blended.

Dollop the cheesecake mixture over the blondie batter and swirl in small amounts of pistachio paste.

Bake for 30 to 35 minutes until edges are golden and center jiggles slightly.

Cool completely on a wire rack before refrigerating for at least one hour.

Lift the blondies out using the parchment and slice into squares to serve.