Preheat the oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper, ensuring there’s enough overhang for easy removal later.

In a mixing bowl, cream together the softened butter and powdered sugar until light and fluffy, about 2-3 minutes using an electric mixer. Add in the vanilla extract and mix until incorporated.

In another bowl, whisk together the all-purpose flour, cornstarch, and salt. Gradually add the dry mixture to the wet ingredients, mixing until well combined. Be careful not to overmix!

Gently fold in the chopped pistachios, ensuring they are evenly distributed in the dough.

Pour the shortbread mixture into the prepared baking pan and press it down evenly with your fingers or a spatula.

Spread the raspberry jam over the shortbread base evenly, ensuring it covers the entire surface.

Bake in the preheated oven for 25-30 minutes or until the edges are lightly golden and the jam is bubbling.

Allow the bars to cool in the pan for at least 10 minutes before removing them using the parchment paper overhang. Once cooled completely, slice into squares and enjoy!