1 package unflavored gelatin
1 ¼ cups crushed vanilla wafers, divided
2 lemons
4 eggs, separated
1 cup granulated sugar, divided
1 cup whipping cream
In a small bowl dissolve gelatin in ¼ cup cold water.  Set aside.
Spray a 9 X 5 inch loaf pan lightly with cooking spray, then line the pan with a sheet of plastic wrap, allowing the wrap to hang over the long edges of the pan (the wrap will come about halfway up the short sides of the pan).  Sprinkle ½ cup of crushed vanilla wafers in the bottom of the pan: set aside
Zest the lemons: set the zest aside.  Squeeze the lemons
In a saucepan, whisk the egg yolks with ½ cup of the sugar, the lemon zest and the lemon juice.  Cook over low heat, stirring constantly until the mixture is boiling and thickened.  Add the gelatin and stir until well-dissolved;  remove from heat.  Cool to room temperature.
When the mixture is cool, whip the egg whites until they begin to stiffen, and then slowly beat in the remaining ½ cup sugar until whites are stiff but not dry.  Set aside.
In a separate bowl beat whipping cream until it holds its shape.
Fold the whipping cream into the yolk mixture.  Fold in the egg whites.  Spoon the mixture into the prepared pan and tap gently on counter to remove air bubbles.  Top with remaining crushed wafers.
Chill overnight.  To serve, run a small spatula along the short edges of the pan.  Place an inverted serving plate on top of the pan, and then flip the plate and pan together.  Peel off the plastic wrap.  Sprinkle with wafer crumbs, if desired.