Special equipment: 10-inch tube pan

 

CAKE:

9 large eggs whites, at room temperature
1 teaspoon cream of tartar
1/8 teaspoon salt
5 large egg yolks, at room temperature
1 1/2 cups sugar
1 cup cake flour; sifted 5 times
2 1/2 teaspoons grated lemon zest

 

CUSTARD ICING:

1 envelope unflavored gelatin
1/2 cup fresh lemon juice
3 1/2 cups heavy or whipping cream
5 large egg yolks, at room temperature
3/4 cup sugar
2 teaspoons grated lemon zest

 

GARNISH:

Fresh lemon balm or lemon leaves (optional)
3 cups fresh berries (blueberries, raspberries, and strawberries)

 

1. Position a rack in the center of the oven and preheat the oven to 200 degrees F.

 

2. Prepare the cake; Grease and flour a 10-inch tube pan.

 

3. Using an electric mixer, beat the egg whites until frothy. Add the cream of tartar and salt, and beat until the whites are stiff but not dry.

 

4. In another bowl beat yolks until they are pale yellow and thick. Gradually add the sugar, and beat until the mixture is pale yellow and a slowly dissolving ribbon forms when the beaters are lifted.

 

5. Gently fold half the whites into the yolk, then gently fold in the flour. Fold in the remaining whites and the lemon zest. Pour the batter into the prepared pan, and bake 15 minutes.

 

6. Increase the heat to 225 degrees F and bake another 15 minutes. Increase the heat to 250 degrees F and bake another 15 minutes.
Increase the heat to 275 degrees F and bake another 15 minutes. Finally, increase the heat to 300 degrees F and bake until the cake is springy to the touch, about 15 minutes. Cool the cake in the pan.

 

7. Remove the cake from the pan and carefully cut it into three even layers, using a serrated knife. Set the layers aside.

 

8. Prepare the custard icing: Sprinkle the gelatin over the lemon juice in a small bowl. Heat 1 1/2 cups of cream in the top of a double boiler placed over simmering water until just warm, 3 to 4
minutes.

 

9. Using an electric mixer, beat the egg yolks in a medium-size bowl until they are pale yellow. Gradually beat the sugar, then blend in the warm cream. Return the mixture to the top of the double boiler. Stir over medium-high heat until the custard thickens and coats the spoon, about 10 minutes.

 

10. Mix in the softened gelatin and the lemon zest, and stir until the gelatin has dissolved. Refrigerate until chilled but not set. Whip the remaining 2 cups of cream until it forms soft peaks, and fold it into the chilled custard.

 

11. Assemble the cake, spreading each layer with a generous amount of custard. Spread the remaining custard in a swirling pattern over
the top and sides of the cake. (The cake can be prepared 1 day ahead. Tent foil loosely over the cake so that you don't disturb the icing, and refrigerate.)

 

12. To serve, line a platter with lemon balm or lemon leaves. Carfully transfer the cake to the platter, using two spatulas as an aid. Spoon the berries onto the center of the cake and over the
leaves. Let the cake stand at room temperature for 30 minutes before serving.

 

Serves 10