Preheat the oven to 350F. Line a jelly roll pan with parchment paper or a silicone mat; do not grease the sides.

Place the eggs and cream of tartar into a clean stand mixer bowl. Whisk on high speed for 8 to 10 minutes, until the eggs are thick, pale and voluminous. In a separate bowl, combine the almond flour, stevia and baking powder; stir together. Once eggs are whisked, add the vanilla extract and then gradually sift in the dry ingredients. Fold the dry ingredients into the eggs gently but thoroughly, mixing well after each addition.

Pour the cake batter into the prepared pan and spread evenly to the edges with a spatula. Bake the sponge cake in the preheated oven for 20 to 22 minutes, until golden brown on top. Immediately after removing the cake, run a knife along the edge of the pan to release the cake. Place a clean kitchen towel over the cake, top with a wire cooling rack and then turn over. Remove the pan and remove the paper/mat. Using the towel, gently roll the sponge cake into a roll and allow it to cool completely at room temperature.

While cake is cooling, prepare the filling. Place the softened cream cheese, stevia and vanilla into a large bowl. Use a mixer to cream the cheese for 2 to 3 minutes, until it's creamy and clump-free. Add 1/2 cup raspberries and blackberries and mix again, crushing the berries into the cheese. In a separate bowl, whisk the chilled heavy cream for 3 to 4 minutes, until stiff peaks form. Add the cream cheese mixture to the whipped cream and mix again for 30 seconds; do not over mix!

To assemble the cake, gently unroll the cooled sponge cake; it's okay of cracks form. Spread all of the filling over the sponge cake, spreading it evenly to the edges. Top the filling with a few handfuls of fresh berries, such as blueberries, raspberries and blackberries. Using the towel to help, gently roll the sponge cake back up the same way and roll the cake onto a serving tray. (See my video recipe for details!)

For the keto whipped cream, place the chilled heavy cream, stevia, vanilla and salt into a mixer bowl. Whisk for 3 to 4 minutes until stiff peaks form. Transfer the cream into a pastry bag, I used French star tip #4ft. Pipe dollops of cream on to the cake, then garnish with more berries and mint leaves. If not serving right away, keep cake refrigerated.