Meyer Lemon Semifreddo

8 Servings. Measure the lemon juice, sugar, and butter into a nonreactive saucepan, and set over low heat. Briefly whisk together the eggs and egg yolks in a bowl. When the butter has melted, whisk some of the warm liquid from the saucepan into the egg mixture, then stir the warmed eggs back into the liquid in the saucepan. Stir constantly with a wooden paddle or a heatproof spatula until the curd starts thickening and looks slightly jelled. Press the lemon curd through a strainer into a container. Cover and refrigerate until ready to use. (The lemon curd can be made up to a week in advance.) To make the lemon syrup: Heat the water and sugar together until the sugar has dissolved. Remove from the heat, and stir in the Meyer lemon juice and the kirsch, if using. To assemble the semifreddo: Remove the parchment paper and cut the sponge cake into two pieces that will fit a 2-quart baking dish or souffle mold. (You will have extra sponge cake left over that can be frozen for future use.) Whip the cream until it forms soft peaks. Fold together the whipped cream and the chilled lemon curd. Spread 1 cup of the lemon-cream mixture evenly in the bottom of the baking dish. Place one of the pieces of sponge cake on top of the lemon cream. With a pastry brush, soak the sponge cake with about 1/2 cup of the lemon syrup. Spread 1 more cup of the lemon cream evenly on top of the first sponge cake layer, and sprinkle with 1/2 cup of the amaretti crumbs. Lay the second piece of sponge cake on top and soak it with the rest of the syrup. Top with the remaining lemon cream spread in an even layer. Refrigerate, uncovered, for 30 minutes, then cover with plastic wrap, and refrigerate until ready to serve - preferably overnight, to give the semifreddo time to mellow. Before serving, sprinkle the remaining amaretti crumbs over the top. Serve the semifreddo with raspberry or blackberry sauce, or with berries tossed in sugar. Note: If you use Eureka lemons instead of Meyer lemons, increase the sugar by 1/4 cup. Sponge Cake One 9 by 3-inch round cake or one 12 by 18-inch rectangular cake 5 eggs, separated, at room temperature 1/2 cup cold water 1 1/2 cups sugar 1 teaspoon vanilla extract 1 1/2 cups cake flour 1/2 teaspoon baking powder 1/4 teaspoon salt Position the oven rack in the center of the oven and preheat the oven to 350 degrees F. Lightly butter only the bottom of a 12 by 18-inch sheet pan or a 9 by 3-inch round cake pan. Either cover it with a sheet of parchment paper or dust it with flour and tap out any excess. In an electric mixer running at medium speed, whip together the egg yolks and the water for 1 minute. Lower the mixer speed and add the sugar and vanilla extract, then increase the mixer speed to high and continue beating for 5 minutes, until a ribbon forms when you lift the whip. While the egg yolks and sugar are beating, sift together the flour, baking powder, and salt. Once the egg yolks form a ribbon, beat the egg whites in another bowl, until they form soft drooping peaks when you lift the beater. Incorporate the flour mixture into the egg yolk mixture by sifting the dry ingredients over the yolks with one hand and folding with a whisk with the other. Set the bowl on a damp towel to steady it while you sift and fold. When the flour is completely incorporated, use a rubber spatula to fold in the beaten egg whites. Pour the batter into the prepared sheet pan or cake pan and spread it quickly in an even layer with an offset metal spatula or a rubber spatula. Bake for 15 to 18 minutes in a sheet pan, or about 45 minutes in a cake pan, until the top is brown and the cake springs back when you touch it. Store at room temperature. Raspberry Sauce 1 cup 1-pint basket raspberries (2 cups) 1 1/2 tablespoons sugar 1/4 cup water 1/2 teaspoon lemon juice Optional: 1 teaspoon kirsch or framboise [we used kirsch] Pass the raspberries through a food mill fitted with a fine disk, or puree the raspberries in a food processor and press through a sieve to remove the seeds. Heat the sugar and water together until the sugar is dissolved. Stir into the raspberry puree and add the lemon juice and the kirsch or framboise, if desired. Taste and, if necessary, adjust with additional sugar, lemon juice, or kirsch or framboise.