In a small saucepan, combine the egg yolks, 1/2 cup sugar, and fresh lemon juice. Stir continuously over low heat for about 4-5 minutes until the mixture thickens like a custard. Be careful not to let it boil.
Remove the pan from the heat and let the lemon mixture cool down completely. You can place the pan in an ice bath to speed this up, stirring occasionally.
While the lemon mixture cools, in a separate clean bowl, beat the egg whites until they form stiff peaks.
In another bowl, whip the heavy cream with the remaining 1/2 cup sugar until soft peaks form.
Gently fold the cooled lemon mixture into the beaten egg whites, then carefully fold in the whipped cream until everything is well combined and fluffy.
Spread about two-thirds of the finely crushed vanilla wafers evenly across the bottom of an ungreased 8x8 or 9x9 inch baking pan.
Carefully pour the creamy lemon mixture over the crumb base.
Sprinkle the remaining crushed wafers over the top for a delightful finish.
Place the dessert in the freezer for at least 3-4 hours, or until it's firm and perfectly chilled.
When ready to serve, you can let it sit out for a few minutes to soften slightly, then slice and enjoy your refreshing summer treat!