Classic Sponge Cake: Getting started
1. Line bottom of 9-inch (2.5 L) springform pan with parchment paper; grease side. Set eggs in bowl of warm (100°F/38°C) water for 5 minutes.
2. In electric stand mixer on medium-high speed, beat eggs until foamy. Gradually beat in sugar until pale yellow and batter falls in ribbons when beaters are lifted, about 10 minutes. Transfer to large wide bowl. Fold in orange rind and vanilla.
