From The Sono Baking Company Cookbook, by John Barricelli 2010
2 Tablespoons cold water
1 teaspoon powdered unflavored gelatin
6 large egg yolks
Grated zest of 4 lemons (about 4 teaspoons)
1/2 cup lemon juice (from 3-4 lemons)
3/4 cup sugar
1/8 teaspoon kosher salt
1/2 cup (1 stick) unsalted butter, cut into 1/2" pieces
1/2 cup heavy cream
1 Tablespoon sugar (optional)
In a small bowl sprinkle the cold water over the gelatin. Set aside.
In a medium saucepan, combine egg yolks, lemon zest, lemon juice, sugar and salt and whisk to combine. Set over medium heat and cook, stirring constantly, until the mixture has thickened enough to coat the back of a wooden spoon, about 5 minutes. Do not boil. Whisk in gelatin.
Strain through a fine mesh strainer into the bowl of a standing mixer fitted with the paddle attachment. Beat until slightly cooled, 2-3 minutes. Beat in the butter a little at a time, and continue beating until smooth and completely cooled. Transfer to a large bowl and let stand until the gelatin just begins to set, about 10 minutes.
Wash and dry the mixer bowl. (Taste the lemon mixture. If it tastes too sour for you, beat the cream with 1 Tablespoon of sugar. If not, proceed.) Add the cream and beat with the whisk attachment until medium peaks form. Fold into the cooled lemon mixture and refrigerate until very cold and the mousse is set, 2-3 hours.
Yield: 4 servings--serve with berries or spoon over pound cake etc.