Preheat oven to 350°F.
In a medium bowl, mix together softened butter and powdered erythritol until well blended and smooth.
Add pumpkin puree, eggs, and vanilla to butter mixture and blend well.
In a separate bowl, add pumpkin pie spice, almond flour, protein powder, and baking powder. Mix together with a fork to blend.
Add dry ingredients to wet ingredients and mix until well incorporated.
Line a cookie sheet with parchment paper and spray parchment paper with cooking spray.
Spread the cake batter across the entire cookie sheet evenly.
Tap the cookie sheet on the counter a couple times to get out any bubbles and to even the batter out. Put it on the middle rack of the oven.
Bake for 10-15 minutes. It will spring back a bit when touched and a toothpick comes out clean when inserted into the center of the cake.
When cake is done, let cool for 5 – 10 minutes. After it has cooled for a few minutes, roll the cake with the parchment paper, starting from the short end. Try to make sure that the roll is tight as you roll.
Leave on the counter to cool completely, at least 1 hour. Make the filling as the cake cools.
Place softened butter and cream cheese in a medium bowl.
Beat butter and cream cheese together until smooth.
In another bowl, add heavy cream and beat until whipped cream.
Add the whipped cream to the butter and cream cheese mixture.
Add liquid stevia and beat all together until smooth.
After the cake has cooled and the filling is made, unroll the cake gently so that it does not crack.
When completely unrolled, spread the filling over the whole cake, leaving a bit of space at the end without filling.
Roll the cake back up without the parchment paper. Make sure you keep it tight, but not too tight because the filling will spill out.
Wrap it in plastic wrap.
Place in the refrigerator for a couple hours to overnight to set.
Garnish with a dusting of powdered erythritol (optional).
Store in the refrigerator.