preheat oven to 350*. grease and flour 12 cup bundt pan. For streusel: combine brown sugar, 1 teaspoon cinnamon, and allspice in a small bowl. Cut in 2 teaspoons butter with pastry blender or two knives until mixture is crumbly. Set aside. For batter: Combine flour, 1 tablespoon cinnamon, baking soda, and salt in medium bowl. Beat granulated sugar and 1 cup butter in large mixer bowl until light and fluffy. Add eggs one at a time, beating after each addition. Add pumpkin, sour cream, and vanilla; mix well. Gradually beat in flour mixture. To assemble: spoon half the batter into the prepared pan. Sprinkle streuesel over batter, not allowing streuesel to touch the sides of the pan. Top with the remaining batter. Make sure batter layer touches edges of pan. Bake for 55 to 60 minutes or until a toothpick comes out clean. Cool for 30 minutes in pan on wire rack. Invert onto wire rack to cool completely. drizzle with glaze. Glaze: combime powdered sugar and milk in a small bowl; stir untill smooth.