Brush graham cracker crust with 1 beaten egg white and place in oven for 6 minutes. Remove crust from oven and reduce oven temperature to 325°F.
Blend cream cheese, sugar and lemon zest on lowest speed. Alternatively, mix by hand using a spatula until no lumps remain. Scrape bowl well.
Add one egg at a time, waiting for each to be fully incorporated, and scraping bowl and beater/spatula between additions.
Add sour cream and vanilla and pour batter into graham cracker crust.
Place in oven and bake until center of pie no longer trembles, about 43 minutes. Remove from heat and when cool enough to handle place in refrigerator.
To prepare cranberry topping and sauce, use a non-reactive saucepan to bring cranberries, water and sugar to a boil. Simmer on low for about 5 minutes. Remove from heat.
Puree cranberry mixture to a smooth consistency using either an immersion blender directly in pan or transfer to a blender. If you wish, pour mixture through a sieve to remove seeds.
Divide mixture in half and refrigerate half to use as cranberry sauce later. Use remaining half for cranberry topping.
Mix water and gelatin well and set aside for at least 3 minutes to dissolve. Add gelatin to still warm cranberry mixture. (If needed, reheat cranberry mixture until almost hot before adding gel) and mix well.
Remove cheesecake from refrigerator and pour warm mixture onto surface of pie. Return to refrigerator.