A perfect tart for Passover. If you want to use it for non-Passover meals, then replace the potato starch (which is the only thickener allowed) with regular cornstarch. It can be made up to three days ahead of time, but do not fill the shell until a few hours before serving.

Shell:

4 egg whites

¾ cup sugar

1 teaspoon lemon juice

½ cup grated chocolate

Lemon Mousse:

3 eggs

½ cup sugar

½ cup plus 1 tablespoon lemon juice

1 tablespoon grated lemon rind

2 tablespoons potato starch

1 cup water

Preheat oven to 250 F.

Line a baking sheet with parchment paper.

Beat egg whites in an electric mixer until frothy. Slowly beat in sugar. Continue to beat until egg whites are thick and glossy and stand up stiff and straight when beaters are lifted out. Beat in lemon juice. Gently fold in grated chocolate.

Spoon mixture onto parchment paper and spread into a 10-inch round. Hollow out the centre pushing meringue mixture to the sides. The sides will be about 2 inches high. It should look like a pie shell.

Bake for 1½ to 2 hours or until barely browned and dry. Turn oven off and leave for about 4 hours to cool. Remove from parchment paper and place on serving dish.

Whisk together eggs, sugar, lemon juice and lemon rind in a pot to make mousse.

Combine potato starch and water and stir into lemon mixture.

Bring to boil over medium heat, whisking constantly. Remove from heat and pour through a strainer into a separate bowl. Cool. Spoon into meringue shell. Top with Passover whipped topping or whipped cream. Serves 8.