Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper and lightly grease it to prevent sticking.
In a mixing bowl, combine the almond flour, coconut flour, baking powder, xanthan gum, pumpkin pie spice, and salt. Whisk until smooth and set aside. Tip: Make sure to sift the flours to avoid clumps.
In a separate bowl, beat the egg yolks with 1/4 cup of granulated allulose until pale yellow. Mix in the pumpkin puree and vanilla extract.
In another bowl, beat the egg whites until soft peaks form. Gradually add the remaining granulated allulose until stiff peaks form. Tip: Ensure your mixing bowl is clean and dry for the best results.
Gently fold the two egg mixtures together, then add the flour mixture and fold until well combined, being careful not to deflate the air bubbles.
Spread the mixture onto the prepared baking sheet. Bake for 15 minutes or until the cake feels spongy. Remove from the oven and let it cool for 15 minutes.
Place a cutting board on top of the cake, carefully flip it over, and remove the parchment paper. Let the cake cool until just warm.
While the cake cools, beat the whipping cream, powdered allulose, and vanilla extract in a bowl until stiff peaks form. Tip: Ensure the whipping cream is very cold for best results.
Spread the filling evenly over the cake. Roll the cake loosely into a log. Cover with plastic wrap and place it in the freezer to firm up for at least an hour.
Remove from the freezer about 10 minutes before serving. Dust the top of the roll with a bit of powdered sugar substitute. Slice and enjoy!
Notes
For a festive touch, sprinkle some extra pumpkin pie spice on top before serving.