Grease (or Pam) bundt cake pan.
In mixing bowl, combine cake mix, puddings, oil, water, eggs, & 2 Tbsps. cinnamon with mixer.
Pour half of the batter into bundt pan.
In small bowl, combine brown sugar & 2 Tbsps. cinnamon. Sprinkle brown sugar mixture over cake batter in pan.
Pour remaining cake batter on top of brown sugar mixture.
Bake 40-45 minutes at 350 degrees.
Let cake rest in pan for 10 minutes, then invert onto serving plate.
Mix powdered sugar and milk to form a glaze. Add more sugar to achieve desired consistency. Drizzle over cooled cake.