Lightly brush graham cracker crust with egg white. Place in preheated oven for 5 minutes. Remove from oven. While the crust cools, prepare filling.
Pour heavy whipping cream into a medium-sized bowl. Use an electric mixer to stir until stiff peaks form (about 10 minutes).
Zest limes before squeezing for juice.
Add lime zest, sweetened condensed milk, lime juice, and sour cream to heavy cream. Stir with spoon until evenly combined.
Pour mixture into prepared crust. Smooth evenly around crust. To garnish, place 3 sliced limes in center. Add 8 vanilla wafers around center (see photo).
Cover and refrigerate 4 hours up to overnight.
FREEZER OPTION. The covered pie can be stored in freezer for at least 4 weeks. Make sure it's in a pie plate safe for freezing. Place in a larger freezer bag. Seal tightly. Thaw at least 30 minutes before serving or longer if necessary.