Preheat oven to 350 degrees F (175 degrees C). Grease a 9 inch pie plate.
In a medium bowl, mix together the melted butter, graham cracker crumbs, sugar and cinnamon. Press into the bottom and up the sides of the prepared pie plate.
In a large bowl, beat cream cheese until smooth. Gradually beat in sweetened condensed milk until smooth. Beat in eggs one at a time, then stir in vanilla. Fold in chocolate chips.
Pour filling into prepared crust. Bake in preheated oven for 35 minutes, or until center is almost set.