(Makes 2 lunch box-sized cakes) Prepare eggs at room temperature, and warm the milk and butter before use.
Mix the room temperature eggs and sugar, then heat over a double boiler to about 40°C (until the sugar granules are no longer visible).
Whip at medium speed (level 3) for 30 seconds, then at high speed (level 5) for 5 minutes, and finish at low speed (level 1) to smooth the batter.
Bake at 170°C for 20 minutes in an oven preheated to 180°C for 10 minutes.