Preheat oven to 350° F | 175°C. Line a 8” cast iron skillet (or pie dish) with baking/parchment paper and set aside.
In a large bowl, whisk the butter, sugar and vanilla until light and creamy. Whisk in the egg and orange zest until combined.
Add the flour, baking soda and salt, and mix the dry ingredients into the wet until just combined.
Fold in half of the chocolate chips and half of the pistachios.
Spread half of the cookie dough evenly onto the prepared skillet.
Melt the pistachio cream in the microwave for 30 seconds until it becomes thinner in consistency. Spread the pistachio cream over the cookie dough in the skillet evenly to 1-inch of the edges.
Top with remaining cookie dough, smoothing the layer with the back of a metal spoon (and your fingers if you need to). Sprinkle with remaining chocolate chips and chopped pistachios.
Bake in preheated oven for 20 minutes for a gooey cookie, or cover after 20 minutes with aluminum foil and bake for a further 10 minutes for a 'set' cookie. Cool for about 10 minutes before serving.
Notes
Tip: To take your pistachio cream skillet cookie to the next level, add a generous dollop of ice cream to the top of your cookie while it's still warm.