1. Prepare the Crust:

1. Preheat oven to 375°F (190°C). Line a 10×15 inch jelly roll pan with parchment paper. In a large bowl, beat egg yolks with 1/2 cup sugar until pale and thick. Beat in vanilla.
2. In a separate bowl, sift together flour, cocoa powder, and salt. Fold into the egg yolk mixture. In another clean bowl, beat egg whites until soft peaks form. Gradually add remaining 1/4 cup sugar and beat until stiff peaks form. Gently fold into the chocolate batter.
3. Spread batter evenly into the prepared pan. Bake for 12-15 minutes, or until the cake springs back when touched. Immediately turn the cake out onto a clean kitchen towel dusted with cocoa powder. Carefully peel off the parchment paper. Starting from a short end, roll the cake and towel together into a log. Let cool completely on a wire rack.
4. For the frosting, heat the heavy cream until just simmering. Pour over the chocolate chips in a bowl, let sit for 2 minutes, then whisk until smooth. Let ganache cool to room temperature. In another bowl, beat the butter and powdered sugar until light and fluffy. Gradually beat in the cooled chocolate ganache until frosting is smooth and spreadable.
5. Unroll the cooled cake. Spread an even layer of frosting over the cake. Re-roll the cake tightly, without the towel. Place seam-side down on a serving platter. Frost the outside of the log. Use a fork to create bark-like textures in the frosting. Chill for at least 1 hour before serving.