Irish Cream Chocolate Cheesecake

Preheat oven to 375 F.
For the crust: In a bowl mix the Graham cracker crumbs, melted butter and cinnamon until thoroughly combined and the texture of sand. Press mixture into the bottom and up the sides of a 9-inch springform pan. Set aside. (We are not cooking this crust before we add the filling).
For the filling, I recommend using a standing mixer or a hand mixer. In a mixing bowl combine cream cheese, sour cream, sugar and melted (and cooled) chocolate. Beat on medium to high speed until mixture is smooth. Remember to scrape the sides of your bowl a couple of times. Mix in eggs, liqueur, whipping cream or milk and vanilla.
Pour filling mixture into the crust lined pan. Set your springform pan on a sheet pan or other shallow baking pan so that it doesn't leak during baking. Set the pans in the oven and bake for 55 minutes to an hour. Your cheesecake may puff up souffle like, which is awesome and gives a very nice texture. You want the top to just be set, with still a bit of jiggle when you move the pan. At this point, remove the cake from the oven.
Allow cake to cool in the springform pan on a wire rack. When it has come to room temperature, slide a knife around the inside of the srpingform ring to loosen the cake. Remove the ring and allow the cake to cool completely. Cover well and chill in the fridge for at least 4 hours before serving.