Swiss Roll Cake

Cake

1. Preheat the oven to 350° and prep a 17x12 inch rimmed baking sheet by spraying it with non-stick baking spray and lining it with parchment paper. Be sure to let the parchment paper have at least 1 inch overhang on all sides. Spray the parchment lightly with the non-stick baking spray.
2. In a medium bowl whisk together the flour, cocoa powder, baking powder, instant coffee and salt. Set aside.
3. In a large bowl whisk together the egg yolks and sugar until well combined and light in color. Add in the sour cream, butter and vanilla extract and whisk until combined. Fold in the dry ingredients until just combined.
4. In another bowl whip the egg whites until stiff peaks form. Fold 1/3 of the whipped egg whites into the batter until combined and then add the rest and fold until just barely combined and no white streaks remain.
5. Spread the cake batter evenly into the prepared pan and bake for 10-12 minutes, until the center of the cake springs back when gently pressed on.
6. Let the cake cool for just about 2 minutes. Meanwhile prepare a clean kitchen towel by dusting it lightly with powdered sugar. Once the cake has cooled for 2 minutes and is still pretty hot, run a knife around the edges and then very carefully and quickly turn the cake out onto the kitchen towel. Carefully and slowly peel back the parchment paper from the cake, making sure not to tear the cake at all. Dust the cake with more powdered sugar.
7. Starting from the short end, use the towel to roll the warm cake snuggly so the towel is being rolls up inside it. Place the towel with the cake’s seam side down and let it cool completely, about an hour.
8. Gently unroll the cake from the kitchen towel. Make sure none of the cake sticks to the towel as it’s unrolled.

Filling

1. Whip the cream, powdered sugar, and vanilla together until medium stiff peaks form.
2. Spread the cream over the cake, leaving about ½ inch border along one short end free of cream.
3. Gently roll the cake up, carefully pulling the towel off the outside of it as it is rolled up.
4. Carefully wrap the cake with plastic wrap and chill for 2-3 hours, or overnight.
5. When ready to serve, unwrap the cake and place on a cooling rack with parchment or wax paper underneath.
6. Prepare the ganache and pour over the top of the cake. Let the ganache set before carefully transferring the cake from the rack to the serving plate.

Ganache

1. Place the chocolate in a small bowl. Heat the cream in the microwave until steaming but not boiling, about 1 minute. Pour the hot cream over the chocolate and let it sit for a few minutes. Use a whisk to combine the chocolate and cream until smooth.