For the Cake:

• Preheat oven to 375 degrees F. Grease a bakers half sheet pan and line it with parchment paper. Grease and flour paper.
• Beat egg whites in large bowl until soft peaks form; gradually add 1/2 cup granulated sugar, beating until stiff peaks form. 
  4 large eggs
• In a separate bowl: Beat egg yolks and vanilla in medium bowl on medium speed of mixer 3 minutes. Gradually add remaining 1/3 cup granulated sugar; continue beating 2 additional minutes.
  1 teaspoon vanilla extract
• Stir together flour, cocoa, baking powder, baking soda and salt; add to egg yolk mixture alternately with water, beating on low speed just until batter is smooth. 
  1/2 cup all-purpose flour, 1/3 cup unsweetened cocoa powder, 1/2 teaspoon baking powder, 1/4 teaspoon baking soda, 1/8 teaspoon salt, 1/3 cup water
• Gradually fold egg whites into chocolate mixture until combined. Spread batter evenly in prepared pan.
• Bake 14 to 16 minutes or until top springs back when touched lightly in center and a toothpick inserted comes out clean.
• Dust tea towel: Sift a light layer of cocoa powder over a clean tea towel.
• Roll hot cake: Hold the pan close to the towel and immediately turn the cake out onto the cocoa-dusted tea towel. Starting from one of the short ends, carefully roll the cake and the tea towel up together into a tight log (you can leave the parchment paper attached for now).
• Cool: Allow the rolled up cake to cool completely, on top of a wire cooling rack. (Setting it on a wire rack allows it to cool underneath the roll, and keeps the cake from sweating). Transfer to the fridge to cool for an additional 30 minutes.
• Make Filling: While the cake roll is cooling in the fridge, mix the cream cheese, butter, powdered sugar and peppermint extract together with an electric mixer until fluffy and smooth. Gently stir in desired amount of crushed peppermint candies, to taste. Save a handful for sprinkling on the ganache, at the end, if desired. 
  8 ounces cream cheese, 1/4 cup butter, 1 cup powdered sugar, 1/2 teaspoon peppermint extract, 20 starlight mint candies
• Unroll and frost: Gently unroll the cooled cake and peel off the parchment paper. Smooth a thin layer of filling in an even layer over the cake. Roll up the cake, cover with plastic wrap and refrigerate for at least 1 hour.
• Make the Ganache: Heat heavy cream in a saucepan until hot. Pour over chocolate and stir continuously until the chocolate is melted and smooth. Allow the ganache to cool for several minutes to give it time to thicken up a little.
  1/2 cup heavy whipping cream, 1 cup semi-sweet chocolate chips
• Gently spoon/pour the chocolate ganache over the top of the peppermint roll. Sprinkle additional chopped peppermint candy on top, if desired.
• Refrigerate for at least 20 minutes before serving. Store in the fridge, covered, for up to three days.