Preheat your oven to 350°F (175°C). Line a jelly roll pan with parchment paper and lightly grease with cooking spray.
In a medium bowl, whisk together almond flour, coconut flour, cocoa powder, baking powder, and salt. Set aside.
In a large bowl, using an electric mixer, beat the eggs and granulated erythritol until the mixture is pale, fluffy, and doubled in volume. This should take about 5 minutes.
Gently fold in the dry ingredients into the egg mixture until just combined. Stir in the vanilla extract.
Pour the batter into the prepared pan and spread evenly with a spatula.
Bake for 15 minutes or until the cake springs back when touched.
Remove the cake from the oven and let it cool for a few minutes. Then, invert the cake onto a clean kitchen towel dusted with cocoa powder. Peel off the parchment paper carefully.
Starting at the short end, roll the cake up with the towel and let it cool completely.
While the cake is cooling, make the raspberry whipped cream. In a mixing bowl, whip the heavy cream and powdered erythritol until stiff peaks form. Fold in the raspberries and vanilla extract.
Carefully unroll the cooled cake and spread the raspberry whipped cream evenly over the cake, leaving a small border around the edges.
Re-roll the cake tightly without the towel. Wrap in plastic wrap and chill in the refrigerator for at least 1 hour before serving.
To serve, slice the roll cake and garnish with fresh raspberries.