- For the candied orange zest:
- 2 large, thick-skinned oranges
- 2⁄3 cup water
- 1 cup plus 1 tablespoon granulated sugar
- For the orange mousse:
- 1 envelope unflavored gelatin (2-1⁄2 teaspoons)
- 1⁄4 cup cold water
- 1⁄2 cup boiling water
- 1⁄4 cup granulated sugar
- Pinch of salt
- 1-1⁄4 cups orange juice
- 3 tablespoons Grand Marnier or triple sec
- 1 cup heavy cream
- For the angel food cake:
- 1-1⁄2 cups superfine sugar
- 1 cup all-purpose flour
- 1⁄2 teaspoon salt
- 12 large egg whites, at room temperature
- 1 teaspoon cream of tartar
- 1 teaspoon pure vanilla extract
- 1 teaspoon Grand Marnier or triple sec
- Finely grated zest of 1 small orange
- For the orange glaze:
- 2 cups confectioners' sugar
- 4 tablespoons orange juice
- 1 tablespoon Grand Marnier or triple sec
- 1 tablespoon unsalted butter, softened
- 1 teaspoon finely grated orange zest
To make the candied orange zest: Use a citrus zester or small, sharp knife to remove the colored part of the orange peel in long, thin strips.
In a heavy saucepan, combine the zest with enough water to cover by several inches. Bring to a boil over high heat, reduce the heat slightly and simmer rapidly for 5 minutes. Drain and rinse under cool, running water.
Squeeze one of the oranges for about 1/2 cup of juice (squeeze juice from the other orange if you need more juice). Strain the juice through a fine-mesh sieve to remove any pulp or seeds. Reserve the remaining orange for another use.
In the same saucepan, mix the water, 1 cup of the sugar and orange juice and cook over medium heat for about a minute, stirring occasionally, until the sugar melts. Add the orange zest and bring to a boil over medium-high heat. Reduce the heat to medium-low and simmer for about 10 minutes. Remove from the heat and let the zest cool in the syrup to room temperature.
Drain the zest and reserve the syrup for another use. Transfer the zest to a small bowl and sprinkle with the remaining tablespoon of sugar. Toss to coat and then let the zest stand at room temperature for about 2 hours to give it time to cool and absorb the sugar. Use right away or store in an airtight container for up to 24 hours.
To make the mousse: Fill a large bowl with ice and water and keep it close at hand.
In a saucepan, sprinkle the gelatin over the cold water and let it sit for about 4 minutes to soften. Add the boiling water and stir until the gelatin dissolves.
Stir in the orange juice, sugar and salt. If the mixture does not taste sweet enough, add a little more sugar. Cook over low heat, stirring, until hot and the sugar dissolves. Do not let the mixture boil.
Stir in the Grand Marnier and set the saucepan over the ice water and chill for 15 to 20 minutes, whisking occasionally, until the mousse cools and sets up just a little.
Whip the cream in a chilled metal bowl until soft peaks form. Fold the whipped cream into the jelled mixture. Cover with plastic wrap and refrigerate for at least 2 hours and for up to 8 hours. You will have about 4 cups of mousse.
To make the cake: Position an oven rack in the center of the oven. Preheat the oven to 325Â°F.
In a small bowl, whisk together 1/2 cup of the sugar with the flour and salt. In a clean, dry bowl of an electric mixer fitted with a clean, dry wire whip and set at low speed, beat the egg whites until foamy. Sprinkle with cream of tartar, raise the speed to medium, and beat the egg whites until soft peaks form. Add the vanilla, Grand Marnier and orange zest and continue beating the whites.
With the mixer running, add the remaining cup of sugar, a tablespoon or so at a time, until the stiff but not dry peaks form. Remove the bowl from the mixer. Using a rubber spatula, fold the flour-sugar mixture into the whites just until mixed. Do not overmix.
Scrape the batter into an ungreased 10-inch angel food or tube pan and smooth the top. Bake for 50-55 minutes, until the cake springs back when lightly touched.
Invert the cake pan onto its feet to cool completely. When cool, run a dull kitchen knife around the sides of the cake pan to loosen. Invert the cake onto a plate.
To make the glaze: In the bowl of an electric mixer fitted with the paddle attachment, mix together the confectioners’ sugar, orange juice, Grand Marnier and butter and beat on medium speed until smooth and mixed. Remove from the mixer and, using a rubber spatula, stir in the orange zest.
Spread the glaze over the top of the cake, letting a little dibble down the sides. Spoon mousse into the center of the cake and reserve the rest to pass on the side. Decorate the cake with orange zest and serve.