Separate egg whites and beat until fluffy.
Gradually add sugar and cream of tartar.
Beat until stiff peaks.
Pour into 9" pie dish and press up against the sides.
Bake at 300 degrees for 45-60 minutes.
Cool.
Beat egg yolks.
Stir in sugar, lemon juice, lemon zest, and salt.
Cook in the microwave until thick for 4 minutes (stir every 30 seconds).
Whip whipping cream.
Take half of the whipped cream and fold it into the lemon mixture.
Pour into the cooled crust and top with the remaining whipped cream.
Chill for 24 hours.
The meringue crust will crack as it cools. This is normal.