Adjust the oven rack to the middle position and preheat oven to 350°F and line a large (9x13-inch) rimmed baking sheet with parchment paper. Grease the parchment as well as the sides of the pan and set aside.
Combine all cake ingredients in a blender and blend until completely smooth. Spread the batter evenly onto the prepared pan and use a spatula to even the top. Bake until cake is firm to the touch, springs back when pressed lightly, and edges just begin to take on color, about 20-25 minutes. Run a knife around the edge of cake to loosen it while the cake is still hot. Turn the cake out onto a fresh sheet of parchment paper that has been dusted with powdered monk fruit. Carefully peel off the parchment paper that the cake was baked on and discard removed parchment. Gently roll the cake and fresh parchment into log and allow it to cool completely, about 1 hour.
While the cake cools, prepare the filling. Beat all ingredients together with a mixer to stiff peaks. Adjust sweetener to taste.
When the cake is fully cooled, gently unroll it and spread the filling over top, leaving a 1-inch border all the way around the edge of the cake. Re-roll the cake tightly, removing the parchment as you roll. Wrap tightly with plastic wrap and refrigerate for at least an hour and up to 3 days before slicing. Dust with powdered monk fruit before slicing and serving, if desired. Be sure to wipe the knife clean between slices for best cuts.