Prepare the Cookie Base:

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

In a medium bowl, whisk together the flour, baking powder, and salt.

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

Beat in the egg and vanilla extract.

Gradually add the dry ingredients to the butter mixture, mixing until well combined.

Stir in the chopped pistachios and white chocolate chips.

Press the cookie dough evenly into the prepared pan to form the base layer.

Make the Pistachio Layer:

In a medium bowl, combine the melted butter, powdered sugar, ground pistachios, vanilla extract, almond extract (if using), beaten egg, and salt.

Mix until smooth and well combined.

Pour this pistachio mixture over the cookie base and spread evenly.

Bake the Bars:

Bake in the preheated oven for 30-35 minutes, or until the edges are golden and the center is set. A toothpick inserted into the center should come out clean or with just a few crumbs.

Let the bars cool in the pan on a wire rack for at least 15 minutes.

Topping (optional):

If desired, sprinkle chopped pistachios and white chocolate chips on top of the bars while they are still warm. Let them cool completely.

Serve:

Once cooled, cut into squares and enjoy!