Heat the oven to 350°F, line a baking sheet with parchment paper, and lightly grease the parchment. The prepared surface should look evenly coated so the sponge releases cleanly after baking.

Whisk the almond flour, coconut flour, baking powder, xanthan gum, pumpkin pie spice, and salt in a mixing bowl. Break up any visible clumps so the dry mixture folds smoothly into the egg foam.

Beat the egg yolks with 1/4 cup of the granulated allulose until pale, then blend in the pumpkin puree and vanilla extract. The mixture should look smooth and evenly orange with no streaks of yolk remaining.

Whip the egg whites to soft peaks, then slowly add the remaining granulated allulose and continue beating to stiff peaks. When the whisk is lifted, the peaks should stand sharply instead of drooping over.

Fold the yolk mixture into the whipped whites, then fold in the dry mixture with a light hand. The finished batter should look airy and uniform, with no pockets of dry flour.

Spread the batter across the prepared baking sheet and bake for 15 minutes. The center should spring back gently when touched and feel spongy rather than wet or brittle.

Let the baked sponge stand for 15 minutes, then place a cutting board over it and carefully turn it out. Peel off the parchment gradually to avoid pulling away the delicate surface.

Let the sponge cool until barely warm while beating the whipping cream, powdered allulose, and vanilla extract until stiff peaks form. Very cold cream should hold crisp peaks that stay upright when the whisk is lifted.

Spread the whipped filling evenly over the sponge, roll it loosely into a log, and wrap it in plastic wrap. Place the roll in the freezer for at least one hour so the filling firms for slicing.

Take the roll from the freezer about 10 minutes before serving, unwrap it, and dust the outside with powdered sugar substitute. Cut chilled slices for a defined spiral and a filling that stays neatly in place.