FOR THE CRUST
1 1/2 sticks unsalted butter, room temperature
1 1/4 cups all-purpose flour
1 teaspoon salt
1/2 cup whole blanched almonds or you can buy ground almonds
3/4 cup confectioners' sugar
1 large egg yolk
FOR THE FILLING
5 large eggs
1 1/4 cups granulated sugar
1/2 teaspoon salt
1/2 cup fresh lemon juice (from 6 lemons), plus 2 teaspoons finely grated lemon zest
1/4 cup fresh lime juice (from 4 limes)
2 tablespoons heavy cream (optional)
Garnish: red currants or raspberries and confectioners' sugar
1. Preheat oven to 350 degrees. Make the crust: Butter an 11-inch fluted tart or quiche pan with a removable bottom. Whisk together flour and salt. Pulse almonds with confectioners' sugar in a food processor until finely ground our use ground almonds..
2. Beat butter with a mixer on medium speed until pale and fluffy. Beat in almond-sugar mixture. Add yolk and flour mixture, and beat until combined.
3. Press dough evenly into bottom and up sides of prepared pan. Prick dough all over with a fork. Freeze for 20 minutes.
4. Bake crust for 10 minutes. Remove from oven. Press down bottom and up sides if needed. Bake until golden brown, about 13 minutes more (I pressed down the bottom and sides again). Transfer pan to a baking sheet, and let cool for 15 minutes. Reduce oven temperature to 300 degrees.
5. Make the filling: Beat eggs, granulated sugar, and salt with a mixer on medium-high speed until pale and fluffy. Add juices, zest, and cream, and beat until incorporated. Tap bowl on counter to release air bubbles. Pour into prepared crust. Bake until set, about 25 minutes. Let cool completely. Garnish with currants or raspberries and a dusting of confectioners' sugar.