Apricot Mousse Cake

To make sponge cake layers: Position racks in top third and middle of oven. Preheat to 325 degrees F. Line 2 large baking sheets with parchment paper. Using an 8-inch round cake pan as a guide, draw 3 circles on the parchment paper with a pencil. Turn the paper over (the lines will show through). Lightly coat the paper with cooking spray. (Alternatively, line the baking sheets with foil, coat with cooking spray and dust with flour. Trace the circles with your finger.)

Separate 3 eggs into 2 mixing bowls. Add the fourth white to the bowl of whites. Gradually beat 1/2 cup sugar into the yolks with an electric mixer. Add vanilla. Beat on high speed until the mixture is thick and pale and falls in a ribbon when the beaters are lifted, about 3 minutes.

Wash and dry the beaters. Add cream of tartar and salt to the egg whites and beat on low speed until frothy. Gradually increase mixer speed to high and beat until soft peaks form. Sprinkle in the remaining 1 tablespoon sugar and continue beating until stiff but not dry peaks form.

Spoon one-third of the beaten egg whites onto the egg-yolk mixture. Sift one-third of the cake flour on top; fold in the whites and flour until nearly combined. Repeat with another third of the whites and flour, and then the final third.

Spoon the cake batter onto the three circles, spreading it with the back of a large spoon within the outlines to make layers that are level and smooth.

Bake until the layers are golden and firm when lightly pressed, 12 to 15 minutes, switching the positions of the sheets midway through baking. Immediately slide the layers, still resting on the paper, onto a counter. Slide a thin spatula under the layers to release them from the paper. Cover with kitchen towels and let cool to room temperature.

To make apricot mousse: Put lemon juice in a small bowl and sprinkle with gelatin; set aside to soften. Combine apricots and apricot nectar in a saucepan. Bring to a boil, reduce the heat to low and simmer, covered, just until the apricots are tender, 20 to 30 minutes.

Immediately transfer the hot apricots and liquid and the softened gelatin to a food processor; puree until as smooth as possible. Set a fine sieve over a bowl, transfer the apricot puree to the sieve and work it through with a rubber spatula; discard any coarse pulp that remains. Let the puree cool to room temperature.

Bring about 1 inch of water to a simmer in a saucepan. Combine 1/2 cup sugar, 2 egg whites, cream of tartar and 3 tablespoons water in a metal mixing bowl large enough to fit over the saucepan. Set the bowl over the gently simmering water and beat with an electric mixer on low speed, moving the beaters around the bowl constantly, until an instant-read thermometer registers 140 degrees F. (This will take 2 to 3 minutes.) Increase the mixer speed to high and continue beating over the heat for a full 3 1/2 minutes. Remove the bowl from the heat and beat the meringue until cool, about 4 minutes.

Whisk about one-fourth of the meringue into the cooled apricot puree, then fold in the remaining meringue. Whip the cream and fold it into the apricot mixture.

To assemble cake: To make a soaking liquid, combine Amaretto (or other liqueur) and the remaining 1/4 cup water in a small bowl. Coat a 9-inch springform pan with cooking spray. Place one of the cake layers in the center of the pan, bottom-side up (it will not reach all the way to the perimeter). Brush it with about one-third of the soaking liquid. Spread one-third of the apricot mousse in an even layer on top, filling the gap between the cake and the side of the pan. Top with a second cake layer and brush with half of the remaining soaking liquid. Top with half of the remaining mousse. Repeat with remaining cake, syrup and mousse. Spread the top layer of mousse as smooth and even as possible with a small metal spatula. Cover the cake with a piece of plastic wrap that has been coated with cooking spray. Refrigerate until the mousse is set, about 6 hours.

Remove the plastic wrap from the cake. Melt the preserves in a small saucepan over low heat. Let cool slightly, then pour through a small strainer onto the top of the cake, pressing on the preserves to extract all the liquid. Tilt the cake so that the preserves cover the top. Return to the refrigerator briefly to set the preserves. Run a knife around the outside of the cake to release it from the pan. Remove the pan's outer ring, then smooth the sides with a knife. Garnish with apricot roses and fresh mint sprigs.