Into a food processor, add chocolate sandwich cookies and melted butter; pulse until fine crumbs form.
Press mixture into bottom and sides of a 9-inch tart pan with a removable bottom. Place in freezer while preparing filling.
In a large heat-safe bowl, add semisweet chocolate, vanilla extract and cinnamon, and set aside.
Into a small saucepan, add powdered sugar, heavy cream and butter. Heat over medium heat until just beginning to simmer (do not let it come to a boil), then remove from heat.
Pour over chocolate-cinnamon mixture, then cover with a clean kitchen towel and let sit for 2 minutes.
Add salt to mixture and whisk until chocolate is completely melted, then pour into crust.
Use a spatula to smooth out filling, then top with pomegranate arils. Refrigerate for about 4 hours until set, then slice and serve. Store remainder in refrigerator.