Preheat your oven to 180°C (356°F).
In a bowl, combine the whole wheat flour, wheat bran, spices, salt, and baking powder.
In a separate bowl, beat the eggs with erythritol until thick and fluffy.
Add vanilla and pumpkin purée, and mix gently.
Combine the wet and dry mixtures. The batter should be like thick sour cream — not stiffer.
Spread evenly onto a parchment-lined baking sheet (I use a 40×27cm pan). Bake for 12–15 minutes.
Once baked, roll the hot cake with the parchment into a log and let it cool completely on a rack. Yes, roll it while it's hot — that’s how you avoid cracks.
Blend all the cream ingredients until smooth using an immersion blender.
Once the roll is cool, carefully unroll, spread with the cream filling, and re-roll it using the parchment to help.
Wrap tightly in plastic wrap and refrigerate for a few hours. I personally love it best the next day after a full chill.