Zest three lemons.  In a food processor, pulse the sugar with the lemon zest until it is all incorporated.  

In another bowl, beat the sugar and butter until creamed.  It will be crumbly at first but keep beating.  I use a hand mixer but you could also use a stand mixer.  

Add one egg at a time until incorporated.  Add the lemon juice and salt and mix until combined.  

Pour the mixture into a 2 quart sauce pan on medium heat.  Stirring constantly, heat the mixture until it thickens.  This may take about 10 minutes.  As it begins to simmer, it will thicken (at about 170° F).  Remove from the heat and refrigerate to cool.

Place the vanilla wafers in a food processor.  Pulse until the cookies are all crumbs.  Add the melted butter and stir to combine.

Press the mixture into the mold you are using - cheesecake pan, pie pan, or mini cupcake tins.  You can either bake at 350° F for 10 minutes or place in the freezer for 15-20 minutes to let the crust set.

Once the lemon curd is cooled completely, in a medium sized bowl, mix the cream cheese with a hand mixer.  Once it is smooth, add the lemon curd and powdered sugar.  Mix until it is smooth.  

Spread the mixture into the desired pan.  Allow to cool in the refrigerator for at least 4 hours or over night.  Decorate with whip cream and fresh lemon slices.