Preheat oven to 350 F and line 11x17 pan with parchment paper.
Whisk together the dry ingredients, almond flour, coconut flour, baking powder, xanthan gum, cinnamon, ginger and salt.
With an electric mixer beat egg yolks on high with 1/4 cup of the sweetener, until they become pale yellow and thick. Beat in pumpkin puree and vanilla extract.
In a separate bowl beat the egg whites until soft peaks form. Slowly add remaining sweetener, beating until stiff peaks form.
Fold egg yolk mixture into egg white mixture, then gently fold in the ingredients until well combined.
Spread into prepared baking pan and bake 15 to 18 minutes, or until cake just springs back when touched.
Remove and let cool 10 to 15 minutes.
Cover the cake with another piece of parchment and another sheet pan, upside down. Gently but quickly flip the cake on to the new pan and peel off the original parchment paper.
Cover the cake with another piece of parchment and a tea towel and let cool until just warm while making your filling.