Step 1
Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch jelly roll pan with 1 teaspoon butter and line with parchment paper. Grease parchment paper with 1 teaspoon butter.
Step 2
Whisk flour cocoa powder and salt together in a small bowl.
Step 3
Combine egg yolks 1/4 cup confectioners' sugar and vanilla extract in a bowl; beat with an electric mixer on medium-high speed until pale yellow 3 to 4 minutes.
Step 4
Clean the beaters of the electric mixer. Beat egg whites in a bowl on medium-high speed until foamy 1 to 2 minutes. Gradually add 1/2 cup confectioners' sugar and beat until stiff peaks form 2 to 3 minutes more.
Step 5
Fold egg yolk mixture gently into the egg whites. Fold flour mixture in gradually until batter is smooth.
Step 6
Pour batter into the prepared jelly roll pan and spread evenly with an offset spatula.
Step 7
Bake in the preheated oven until a toothpick inserted into the center comes out clean 8 to 10 minutes. Let cool about 30 minutes.
Step 8
Combine 1 cup heavy cream 3 tablespoons confectioners' sugar and sour cream in a bowl; blend with an electric mixer on medium-high speed until stiff 1 to 2 minutes.
Step 9
Turn the jelly roll pan so the shorter side faces you. Spread whipped cream over the cake leaving a 2-inch border at the top. Roll up cake toward the uncovered border letting the parchment paper fall away as you roll. Place roll seam-side down on a serving platter.
Step 9
Place 1/2 cup heavy cream in a small saucepan over medium-low heat until warmed through 3 to 5 minutes. Remove from heat and stir in chocolate chips. Let stand until chocolate softens about 3 minutes. Stir with a spatula or wooden spoon until ganache is smooth and creamy.