Preheat the oven to 350 degrees F (175 degrees C). Grease a 9-inch springform pan and wrap the bottom in 2 layers of aluminum foil.

Mix graham crackers, melted butter, sugar, and cinnamon together in a bowl. Add more butter if the mixture seems dry. Press mixture into the bottom of the prepared springform pan.

Mix cream cheese and sugar together in a large bowl until smooth. Blend in Irish cream liqueur. Add eggs 1 at a time. Mix in sour cream, flour, and vanilla extract until batter is smooth. Pour batter into crust. Place filled springform pan into a large, deep baking pan. Add 1 inch of very hot water to the outer pan.

Bake in the preheated oven for 1 hour. Turn off oven and leave cake in the closed oven for 2 hours to cool completely. Chill in the refrigerator before serving, about 1 hour.