Preheat the oven to 350 degrees.
Using a hand mixer or a stand mixer fitted with the paddle attachment, beat sugar, brown sugar and eggs together for 2-3 minutes, or until the mixture is light and foamy.
Add the pumpkin puree and vanilla extract. Mix until combined.
Whisk together the dry ingredients (flour, pumpkin pie spice, baking powder, baking soda, salt).
Add dry ingredients to wet ingredients. Mix on low speed until combined, then scrape down the bowl.
Spread the pumpkin cake batter directly on top of the piped pattern. Smooth it until it is evenly spread over the entire jelly roll pan.
Bake for 15-18 minutes, or until the cake begins to brown along the edges and it springs back to the touch.
While the cake is baking, place a long piece of parchment paper on top of an upside down cookie sheet. You will be turning out your cake on to this, so make sure that the cookie sheet is large enough to fit the entire cake. Also make sure that you have a clean tea towel and powdered sugar at the ready.
Once the cake is out of the oven, run a knife around the edges and immediately turn out on to your prepared parchment paper and cookie sheet.
Peel off the parchment paper to reveal your leaf designs, then sprinkle a generous layer of powdered sugar on top of the cake.
Next, place your tea towel over the sugared cake, followed by the jelly roll pan that you used to bake the cake. Flip the cake back over.
Peel the parchment paper off of the cake and generously sprinkle powdered sugar over this side of the cake as well.
Lastly, use the tea towel to roll the cake up (the towel will remain inside of the cake). Set it on a cooling rack and let it cool to room temperature.