Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9 inch springform pan.
In a medium bowl, mix graham crackers, cinnamon, 2 tablespoons brown sugar, and butter. Press mixture into the prepared springform pan to form a crust. Bake 10 minutes in the preheated oven, until lightly browned.
In a large bowl, blend cream cheese, sweet potatoes, 1/4 cup brown sugar, light cream, eggs, and vanilla. Pour into the baked crust.
Bake pie 1 hour in the preheated oven, placing marshmallows on top to melt during the last 10 minutes.