• Preheat the oven to 350°.

Pumpkin Cake Batter

• Combine the yellow cake mix with the pumpkin pie spice and whisk until the ingredients are incorporated. Add the pumpkin puree, eggs and oil to the dry ingredients and mix until everything is combined well {I used a hand held mixer}.

Cinnamon Swirl Layer

• In a small bowl combine brown sugar and cinnamon. Mix until everything is nicely incorporated.

Assembly and Baking

• Pour half of the cake batter into a 9x13 pan that has been sprayed with nonstick cooking spray and spread into an even layer. Top with half of the cinnamon swirl layer. Then add the remaining cake batter and cinnamon swirl mixture, creating 4 layers. Using a skewer {or butter knife} and swirl the layers together by going back and forth through the cake {this will take a few times}.
• Bake for 35-40 minutes or until a toothpick inserted near the center comes out with only a few crumbs {but no raw cake batter}. Remove from the oven.
• Cool the cake for 10-15 minutes. Then combine the powdered sugar, milk and pumpkin pie spice together in a bowl. Whisk until smooth. Pour the glaze over the slightly warm cake and spread out into an even layer.