Preheat oven to 350 degrees. Grease and flour a 12 cup bundt pan. (I used cooking spray with flour.)Combine streusel ingredients in a small bowl. Mix until mixture is crumbly. Set aside.Combine flour, pumpkin pie spice, cinnamon, baking soda, baking powder, and salt in a bowl. Beat sugar and butter in mixing bowl until light and fluffy. Add eggs, one at a time, beating well after each one. Add pumpkin, sour cream and vanilla, and mix well. Gradually beat in flour mixture.Spoon half of batter into pan. Sprinkle streusel over batter, keeping it in the middle of the pan (don't allow it to touch sides). Top with remaining batter. Make sure batter layer touches edges of pan (batter will be thick!).Bake for 50-60 minutes or until toothpick comes out of middle of cake clean. Cool for 30 minutes in pan on wire rack. Invert onto rack to cool completely.Melt cinnamon chips and shortening in microwave on high for 1 minute; stir until chips are melted and mixture is smooth. Mix together confectioners' sugar and milk until smooth. Drizzle over cooled cake.