This is a fabulous Passover dessert. The three components: meringues, lemon cream, and chocolate-dipped nuts can all be prepared 2-3 days in advance and assembled right before serving. If not using for Passover, substitute cornstarch for the potato starch, add 1/4 teaspoon cream of tartar to the egg whites when whipping them for the meringues, and try using dairy whipping cream and white chocolate-dipped nuts for dairy meals.
Allow the egg whites to stand at room temperature for 30 minutes If you are short on time, place the egg whites in a stainless steel bowl and set it in a bowl of warm water for 2 minutes to bring the whites to room temperature quickly.
Cover two baking sheets with parchment paper. Preheat oven to the lowest possible temperature, 140-175 degrees.
Place the egg whites in the bowl of a mixer. With the whisk attachment, whip the egg whites with the salt about 5 minutes or until soft peaks form; the tips will curl. Gradually add the sugar, beating on high until stiff peaks form; the tips will stand straight and sugar will be dissolved. Fold in vanilla and almond extracts.
Evenly spread the meringues into 12 circles. Flatten slightly so they have a diameter of about 3- to 4-inch circles. Place the two baking sheets in the oven for 4 hours. When they are done, remove from the parchment; if the bottoms are sticky in the center, return them to the oven for longer. You want them completely dried out but not browned. Transfer to a wire rack to cool.
When completely cool, place in an airtight covered container. Store at room temperature for up to 3 days.
Lemon Cream preparation:
In a medium saucepan, combine the sugar and potato starch. Whisk in the water, stirring constantly, until the mixture comes to a boil over medium-high heat. Boil for 1 minute. Remove from heat. Stir in lemon juice.
In a small bowl, stir the egg yolks with a fork. Add a spoonful of the lemon cream to the eggs. Slowly stir the egg mixture into the lemon cream. Continue to cook for 1 minute. Remove from heat. Cool for 15 minutes. Cover the top of the filling with plastic wrap, making sure it touches the cream or a skin will form. Cool to room temperature or refrigerate overnight or up to 2 days in advance.
In a large bowl, with mixer at a high speed, whip the whipping cream. With a rubber spatula, gently fold in 3/4 of the whipped cream into the lemon cream. Reserve rest of whipped cream for dollop on top.
Over a double boiler or in a microwave, melt the chocolate with the margarine. Roll each nut in the chocolate and gently remove with a fork to a sheet of wax paper. Let stand until chocolate is set and shiny (can be put in refrigerator for 5 minutes). Store in an airtight container until ready for use.
Spread half the meringues with lemon cream. Top with remaining meringues. Place a small dollop of whipped cream on the top of each “sandwich” and top with a chocolate dipped hazelnut or cashew. Serve immediately.