Preheat oven to 325°F (163°C). Line two 9-inch cake pans with parchment paper leaving enough overhang around the sides to easily lift shortbread out. (Parchment is used so you can easily remove the shortbread and not cut it while it’s in the pan.)

Using a hand mixer or a stand mixer fitted with paddle attachment, beat the butter on high speed until completely smooth, about 1 minute. Add the granulated sugar and brown sugar and beat together until smooth and creamy, about 1 minute. Add the vanilla, salt, and flour and beat on low speed, gradually increasing to high speed as the mixture combines. Add 2/3 cup of the finely chopped pistachios, reserving the rest for sprinkling on top of the chocolate. Dough will be very crumbly.

Press 1/2 of the dough into each of the prepared cake pans. You want it nice and compact in each pan.

Bake the shortbread for 30 minutes or until lightly browned on top and around the edges.

Remove from the oven and allow to cool for 10 minutes. Carefully remove the shortbread from the pans by picking it up with the parchment paper on the sides. Cut each into 12 wedges. You want to make sure you cut the shortbread while it’s still warm. Allow to cool completely on the parchment before dipping into chocolate.

Melt the chopped chocolate in the microwave in 20 second increments, stopping and stirring after each until completely smooth. Dip the shortbread ends into chocolate and sprinkle with remaining chopped pistachios and sea salt. Allow chocolate to completely set.