LOG: Preheat oven to 350°F. Line 10x16” jelly roll pan (sides too), and grease lining. Beat egg yolks and sugar until pale yellow. Sift flour, cocoa, and baking powder together. Use up to 3 tsp cocoa if you prefer a more intense chocolate taste. Beat in melted butter, then water, sifted flour and baking powder. In separate bowl, beat egg whites and salt into peaks. Fold into the dough. Spread thinly onto pan. Bake 12min. Immediately (and very carefully) reverse cake onto clean cotton towel. Remove lining, and roll the cake with the towel. Let cool. FROSTING: Simmer water and sugar (without mixing, and preferably in heavy-bottom saucepan) until a drop of the syrup forms a soft ball in cold water (15-20 min, or until it reaches 235°F). If the ball breaks when you press on it, add 1tsp water to the syrup and try again. Beat eggs until fluffy. While still beating, add very thin stream of boiling syrup until fully incorporated. Continue beating until mixture is room temperature (about 10 minutes). Add butter. If the cream curdles, beat in 1/4 cup melted chocolate chips or place bowl over steaming water for a few seconds and mix again. Add coffee Extract. Optionally, separate frosting into two batches (one for inside and one for outside of log). Beat another 1/2 cup melted chocolate chips into the outside of log (or entire frosting batch if you did not separate them). ASSEMBLY: Delicately unroll the cake, remove the lining, frost the cake, then tightly roll back up. Frost the outside of the cake. You can choose to cut one edge of the cake and use frosting to “glue” the piece back on top of the log to create a branch. Sprinkle with cocoa powder.