Preheat oven to 180C/350F.
Pistachio Cookies: in a bowl, beat together the butter and sugars until pale and puffy. Add in the egg and mix until well combined. Add in the flour, ground pistachio, baking soda and mix well. Finally, add in the choc chips and mix well. Set aside
Assemble: Cut your croissants in half. On the bottom half, pipe a layer of pistachio cream then followed by a layer of your pistachio cookie dough. Close the croissant with its top half and add a little bit more of the cookie dough on the top, generously sprinkle some chopped pistachios for garnish.
Bake for 12-15 minutes or until the cookie dough on top of the croissant is cooked and slightly golden. Cool slightly then serve.