Preheat oven to 350 degrees and spray a 9x13 pan with non-stick cooking spray. In a large bowl, using an electric hand blender, beat the cream cheese and butter together until smooth. Add brown sugar and blend to incorporate. Add the eggs, pumpkin puree, vanilla and milk, then mix until ingredients are blended. Add dry organic cake mix and blend until smooth.
Pour batter into prepared pan and spread evenly. In a separate bowl, combine all ingredients for the filling. Evenly spread cinnamon filling over batter then use a spoon to gently swirl the mixture into the top layer of the batter.
Bake for 35-40 minutes, until the edges begin to turn golden and a toothpick inserted in the center comes out clean. Cool 15 minutes. Whisk together the milk and organic frosting mix then drizzle over cooled cake. Cut into squares and enjoy!