Make the cake batter using 4 whole egss, 3/4 cup sugar, and 3/4 cup cake flour [I actually used rye & it came out fine]. I do suggest using parchment paper for lining as it likes to stick...not really but the less freaking out about it not looking nice, the better.
1) In a bowl, combine the eggs (at room temperature) and sugar. Set the bowl over a saucepan of simmering water; the base of the bowl should not touch the water.
2) Beat with a handheld electric mixer at medium-high speed until the mixture is very thick and pale, about 10 minutes.
3) Lift out the beaters; the mixure on the beaters should trail back into the surface of the remaining mixture in the bowl to make a ribbon that holds its shape.
4)Remove the bowl from over the pan of water and contiue beating until the mixture is cool, 2-4 minutes.
5) Sift the flour and fold it into the mixture, cutting in to the bottom of the bowl with a rubber spatula or large metal spoon, and turning the batter over, working gently yet thoroughly, to retain the volume of the egg and sugar mixture.
6) Pour the batter into the prepared pan or pans and back as directed. To test if a spongecake is done, press the center lightly with your fingertip; the cake should spring back.
Pour the batter into a greased, bottom-lined, and floured 9 inch round cake pan [or whatever]. Bake in a preheated 350F oven 30-35 minutes. Let the cake cool in the pan 10 minutes, then unmold onto a wire rack and cool completely. Before serving, peel off the lining paper. Dust lightly with confectioners' sugar.