1/4-1/2cupheavy creamstart w 1/4 cup and add a little more cream if needed
Preheat oven to 350 degrees F. and spray a half sheet size baking pan (13 x 18 x 1) with non stick cooking spray.
Place cake mix, eggs, oil, milk, pudding, sour cream and pumpkin into a stand mixer or electric mixer, beating until well combined, about 1 1/2 minutes. Pour into prepared pan, spreading evenly.
Place butter into a microwave safe bowl and melt, about 30-40 seconds. Add brown sugar and cinnamon to bowl, mixing until combined. Drizzle mixture evenly over cake then take a knife and run it through to swirl.
Bake cake for 30-35 minutes, until cooked through and remove. Place powdered sugar and cream into a large bowl and mix until creamy and smooth. Drizzle over warm cake then let cool for 20 minutes before cutting into squares. Refrigerate if not serving same day. Enjoy with milk!