Allow ice cream to thaw out for about 5 minutes and then scoop out ice cream onto a parchment lined baking sheet and spread out into even thickness. Freeze 1-2 hours.
Use a 3-inch round cookie cutter to cut out ice cream disks and freeze the disks until ready to assemble the sandwiches.
Skull Cookies
Cream butter and sugar in a stand mixer with the paddle attachment. Add vanilla and egg and mix on medium speed until incorporated.
Mix dry ingredients in a separate bowl and add to the stand mixer. Mix on medium speed until a dough forms. Wrap dough in plastic and refrigerate for a minimum of one hour.
Press about 2 tablespoons of cookie dough into 4 large silicone skull ice molds, working it down into the mold. The dough should only be about half way full. If you add too much cookie dough, they will be too thick. Freeze for 1 hour and then remove the dough from molds. Keep molded skulls frozen as you repeat with remaining dough.
Preheat oven to 375℉ line baking sheet with parchment paper.
Place frozen molded skulls on a prepared baking sheet and bake for 10-12 minutes until the cookies are just set. Take care to avoid over baking them or they will be too hard for the sandwiches. Cool completely.
Place 7 chocolate sandwich cookies in a mini prep food processor and pulse them into cookie crumbs. Pour the crumbs out onto a shallow plate.
Assemble the Cookies and Scream Sandwiches: Working quickly, remove the frozen ice cream disks from the freezer and sandwich each disk between two skull cookies. Roll each sandwich in the cookie crumbs and place them in the freezer 1 hour and then wrap each individually with plastic wrap to store and serve at a later date.