For the cinnamon streusel, mix together 2 pounds streusel and 1 oz cinnamon.
Mix batter according to manufacturer directions. Spray and line a 9-inch cake pan with parchment paper. Deposit 12 oz prepared batter into the pan, spread batter to the edges. Sprinkle in 0.25oz cinnamon, being careful to reach all the way to the edges in a smooth layer. Carefully deposit another 14oz batter and smooth the top. Sprinkle with 5oz streusel and bake at 360F until cake springs back lightly when touched. Let cake cool completely and depan. Drizzle with glaze.