Preheat oven to 350°F (175°C) and line a 9x9-inch baking pan with parchment paper.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.

Mix in vanilla extract. Gradually add flour and salt, stirring until fully combined into a soft dough.

Fold in the chopped toasted pistachios, reserving a few for sprinkling on top.

Press the dough evenly into the prepared baking pan. Sprinkle remaining pistachios over the top and gently press into the dough.

Bake for 25-30 minutes or until the edges are lightly golden.

Allow bars to cool completely in the pan before dusting with powdered sugar. Cut into squares or rectangles and serve.