Preheat the oven to 350°F and line a 9 x 13 pan with parchment paper on all sides or butter and flour well. Set aside.
First, make the pumpkin cake. In a large bowl, combine the pumpkin puree, sugar, vegetable oil, eggs, and vanilla extract. In a separate bowl, combine the flour, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt.
Incorporate the dry ingredients into the wet, stirring until well combined.
Pour the batter into your prepared pan, and bake for 30 to 40 minutes or until a knife inserted into the middle comes out mostly clean. Transfer to a wire rack to cool completely.
While the cake cools, make the cinnamon sugar streusel. Lower the oven temperature to 300° F and line a baking sheet with parchment paper.
Combine all of the ingredients for the streusel and use your hands to bring everything together until it resembles wet sand and starts to clump together. Use your hands to clump the mixture together into big and small balls and spread out on your baking sheet.
Bake the streusel for 10 to 12 minutes or until light golden brown. Let cool completely.
Once your cake and crumbs are cool, make the cream cheese frosting.
Combine all of the frosting ingredients in a stand mixer fit with the whisk attachment. Beat on low speed, gradually increasing to high. Beat until light and fluffy. Transfer the frosting to a piping bag fit with a large round tip.
Now you are ready to assemble your cake. Use a 6 inch cake ring to cut out 2 cakes from your rectangle. These will be your two top cake layers–you will form the bottom layer from the remaining scraps.
Line a sheet pan with a clean piece of parchment. Clean cake ring and place it in center of the pan. Use 1 acetate strip to line inside of cake ring. Place cake scraps inside ring and use the back of your hand to press scraps together into a flat, even layer (you never see this layer, so it’s okay that it’s messy—but since it’s the base of the cake, it needs to be flat).
Pipe about 1/3 of the frosting on top of the cake layer and sprinkle with about 1/3 cup of the cinnamon sugar streusel. Use your hands to gently press the streusel into the frosting so it will stick.
Place one of the cake layers on top of the streusel and repeat with another third of the frosting and cinnamon sugar streusel crumbs. Repeat with the final layer, pressing down firmly.
Place the cake in the fridge for an hour to set.
When ready to eat, pop the cake out of the cake pan and peel away the acetate from the edges. Enjoy!