Makes 1 large cake.
• 6 eggs, separated
• 1 cup sugar
• ¼ cup boiling water
• 1 Tbs. lemon juice
• ½ tsp. vanilla extract
• 1½ cups flour
• 1½ tsp. baking powder
• pinch of salt
• 4 Tbs. butter, melted and cooled
1. Beat the egg yolks until they are creamy and light, then gradually add the sugar a bit at a time, while you continue beating. Beat the yolks and sugar together until the mixture is pale colored and fluffy—another 10 minutes or so. Gradually add the boiling water, lemon juice, and vanilla and beat another few minutes.
2. Sift together the flour and baking powder and fold it into the egg yolk mixture. Beat the egg whites with a pinch of salt until they hold firm peaks and fold them gently into the batter, using as few strokes as necessary. Pour the melted, cooled butter over the batter, leaving out the milky sediment at the bottom of the pan. Again using as few strokes as necessary, in order not to deflate the egg whites, scoop in the butter.
3. Spoon the batter into a buttered and floured 9- or 10-inch springform cake pan. Smooth the batter lightly in the pan.
4. Bake in a preheated oven at 325 degrees for 40 to 45 minutes if you’re making 1 large cake, slightly less time if you’re making 2 layers. The cake is done when it is golden on top and shrinking away from the sides and when a toothpick inserted in the cake comes out clean.
5. Let the cake cool in the pan for a few minutes, then transfer to a rack until it is completely cool.
6. Sponge cake, as its name indicates, is ideally suited for all those splendid tortes and desserts in which a quantity of rum or brandy is meant to be soaked up by the cake layers.
