Tuesday, March 30, 2010

Meyer Lemon Mousse Cake

The other day I spotted some Meyer lemons at my over-priced, not-so-fabulous, local ‘gourmet’ food shop, and I succumbed. Wasn’t exactly sure what I’d make with them, but they were just too pretty to resist. A cross between a lemon and an orange, the Meyer lemon was named after F.N. Meyer, who originally imported it from China in 1908. Meyer lemons are yellow-orange in color, with a slightly rounder shape and smoother skin than common lemons. Their juice is sweeter and less acidic than that of common lemons. I ultimately decided to use them in a variation of a cake I created for The Cake Book, a genoise cake brushed with sweet ginger syrup and enveloped in a soft lemon-orange mousse. The cake turned out to be delicious, not too tart and not too sweet, with just a hint of spice from the ginger syrup. Note: If you decide to use regular lemons instead of Meyer lemons, you’ll need to increase the sugar in the mousse by ¼ cup or so.

Meyer Lemon Mousse Cake

Makes one 9-inch cake, serving 10

1 cup (3.5 oz/100 g) sifted cake flour
1/8 teaspoon salt
4 large eggs
1/2 cup (3.5 oz/100 g) granulated sugar
1 teaspoon finely grated Meyer lemon zest
1 teaspoon vanilla extract
4 tablespoons (2 oz/57 g) unsalted butter, melted and cooled

Ginger Syrup:
2/3 cup (160 ml) water
1/2 cup (3.5 oz/100 g) granulated sugar
1/2-inch piece fresh gingerroot, peeled and thinly sliced

Meyer Lemon Mousse:
1/4 cup (60 ml) water
2  teaspoons powdered gelatin
1 cup freshly squeezed Meyer lemon juice
1 1/2 tablespoons (.3 oz/9 g) finely grated Meyer lemon zest
1 cup plus 2 tablespoons (8 oz/225 g) granulated sugar
6 large egg yolks
2 tablespoons (30 ml) Grand Marnier or Cointreau (optional)
1 teaspoon vanilla extract
1 1/2 cups (360 ml) heavy cream

Sweetened Whipped Cream
Lemon peel spiral

Make the genoise:
1. Position a rack in the center of the oven and preheat the oven to 350°F. Grease the bottom and sides of a 9-inch round cake pan. Dust the pan with flour and set aside.
2.  In a medium bowl, sift together the cake flour and salt. Whisk to combine and set aside.
3. In the bowl of an electric mixer, whisk together the eggs and sugar by hand. Set the bowl over a saucepan of simmering water, making sure that the bottom of the bowl does not touch the water. Heat the egg mixture, whisking constantly, until the eggs are warm. Transfer the bowl to the electric mixer stand and, using the whisk attachment, beat on high speed until the mixture has tripled in volume, about 8 minutes. Reduce the speed to low and beat in the lemon zest and vanilla extract.
4. Resift one-third of the flour mixture over the batter and gently fold it in with a rubber spatula. In two more additions, sift in the remaining flour mixture, again folding in gently. Have the melted butter in a small bowl. Scoop about 3/4 cup of the cake batter into the bowl and stir until blended. Fold this mixture into the remaining cake batter. Scrape the batter into the prepared pan.
5. Bake the cake for 18 to 22 minutes, until the top springs back when lightly touched and a tester inserted into the center comes out clean. Cool the cake in the pan for 15 minutes. Invert the cake onto the wire rack and cool completely.

Make the Ginger Syrup:
6. In a small saucepan, combine the water and sugar and bring to a boil over medium-high heat, stirring occasionally just to dissolve the sugar. Remove the pan from the heat and add the ginger slices. Let stand at room temperature until ready to use.

Make the mousse:
7. Pour the water into a medium saucepan and sprinkle the gelatin over it. Let the gelatin soften for 5 minutes.
8. Whisk in the lemon juice,  zest, sugar, and egg yolks. Place the pan over medium heat and cook, whisking constantly, until the mixture thickens and reaches 180°F on an instant-read thermometer. Pour the mixture through a fine-mesh sieve into a medium bowl. Stir in the orange liqueur and vanilla extract.
9. Set the bowl containing the lemon mixture in a large mixing bowl filled one-third of the way with ice water (be careful that the water doesn’t splash into the lemon mixture). Stir the lemon mixture frequently until it is completely cool, about 10 minutes.
10. In the bowl of an electric mixer, using the whisk attachment, whip the heavy cream at medium-high speed to firm peaks. Fold the lemon mixture into the whipped cream. (The cake should be assembled now.)

Assemble the cake:
11.  Using a long, serrated knife, cut the genoise cake horizontally into 2 layers. Arrange a cake layer, cut side up, in the bottom of a 9-inch springform pan, centering it so that the gap between the cake and the side of the pan is even all the way around.  Generously brush the cake with half of the Ginger Syrup. Scrape half of the mousse on top of the cake and, using a small offset metal spatula, spread it into an even layer, letting the mousse fill the gap between the cake and the side of the pan. Arrange the remaining cake layer, cut side up, on top, centering it. Brush the cake with the remaining Ginger Syrup. Scrape the remaining mousse on top and spread it into an even layer as before. Refrigerate the cake for at least 3 hours before serving, until set.

Serve the cake:
12. Run a sharp, thin-bladed knife under hot water and wipe dry. Run the knife between the cake and the side of the springform pan, reheating it as necessary. Remove the side of the springform pan. Use a small metal spatula to smooth the mousse on the sides of the cake, if necessary.  Refrigerate the cake if not serving immediately.
13. Garnish the top of the cake with Sweetened Whipped Cream (either piped of dolloped) and a spiral of lemon peel. Cut the cake using a thin-bladed knife and serve chilled.