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

Melt 1 cup of unsalted butter in a medium saucepan over low heat, let cool, then mix with 1 cup of light brown sugar until smooth.

Add 2 large eggs and 1 teaspoon vanilla extract to the butter mixture, stirring until fully integrated.

Sift together 1 cup of all-purpose flour and a pinch of salt, then fold this into the wet ingredients.

Spread the batter into the lined pan, smoothing the top without pressing down too hard.

Beat together 8 ounces of cream cheese with 1/2 cup of granulated sugar until creamy. Add 1 egg yolk and 1 teaspoon vanilla, mixing until combined.

Dollop the cheesecake mixture over the blondie batter, spreading it gently and keeping layers distinct.

Spoon dollops of pistachio paste over the cheesecake layer and swirl gently with a skewer or knife.

Bake for 30 to 35 minutes until golden brown edges and a slightly jiggle in the center.

Let the blondies cool completely, then refrigerate for at least an hour before slicing.