Line a jelly roll pan (15”x10”x1” pan) with parchment paper and grease well. Sift the ½ cup all-purpose flour, ⅓ cup cocoa powder, ¼ teaspoon baking soda and ¼ teaspoon salt.
Separate the 4 large eggs and place the egg whites in a large mixing bowl or the bowl of a stand mixer and the egg yolks in a separate large mixing bowl or bowl of a stand mixer.
Add the Pinch of cream of tartar to the egg whites and whip with a mixer on high until until soft peaks form. Once soft peaks form, gradually add in ¾ cup granulated sugar and continue to beat on high until stiff peaks form.
Add the 1 teaspoon vanilla extract to the egg yolks and mix on high until thick and a soft yellow color, around 3-4 minutes; gently fold into egg whites using a rubber spatula.
Gently fold in the sifted dry ingredients, in three separate additions ensuring no streaks of dry ingredients remain in the batter.
Pour batter into the prepared jelly roll pan and bake @ 375°F for 12-15 minutes until the edges of the cake spring back when touched and a toothpick inserted into the center comes out clean; prepare working surface while the cake is baking. Do NOT over bake.
To prepare working surface: use a clean tea or kitchen towel and dust with powdered sugar.
Once cake is removed from oven, immediately run a sharp knife around the edges of the cake and invert onto the prepared towel. Remove the parchment paper and trim any uneven edges of the cake, if necessary. Slowly roll the cake (with the towel), starting at a short end until the cake is rolled into a log. Place on a wire rack to cool completely.