Step 1.  Preheat the oven to 350 degrees F and cover a 10 x 15-inch cookie sheet with parchment paper.  Spray the parchment paper with cooking spray and dust it with a little cocoa powder.

Step 2.  In a large bowl, whip the egg whites with an electric mixer until stiff peaks form.

Step 3.  Beat together the egg yolks, sweetener, salt, coffee, vanilla extract, and 2 tablespoons of the cocoa powder.

Step 4.  Fold the egg whites into the cake batter.

Step 5.  Pour the batter onto the cookie sheet and spread it out to fill the whole surface.  Bake for 20 minutes.

Step 6.  Remove from the oven and carefully cut around the edge of the cake.  Allow to cool for 10 minutes.

Step 7.  Lay out a clean tea towel and sprinkle 1/4 cup cocoa powder onto the surface of the towel.

Step 8.  Invert the cake onto the cocoa-covered towel and peel off the top piece of parchment paper. Roll up carefully inside a towel and let it cool while you make the filling.

Step 9.  In a large bowl, beat the whipping cream with an electric mixer until stiff peaks form.

Step 10.  In another large bowl, beat together the cream cheese, sweetener, salt, and vanilla until smooth.

Step 11.  Using a spatula, fold the whipped cream into the cream cheese mixture.

Step 12.  After the cake has cooled for at least 20 minutes, unroll the cooled cake from towel, spread on the filling, and roll the cake back up.