Preheat the oven to 350˚F.  

Grease the bottom and sides of a 9-inch springform cake pan. 

For the crust, combine graham cracker crumbs, butter and ¼ cup sugar in a medium mixing bowl.  Spread mixture in pan, packing firmly on the bottom and sides.  Bake the crust for 10 minutes.  Allow crust to cool completely. 

For the filling, place cream cheese in a large mixing bowl and beat on low to medium speed until smooth.  Add the sour cream and mix until combined.  Add one cup sugar, scraping the bowl to mix all ingredients until fluffy.  Add eggs and egg white one at a time and mix until combined.  Slowly add the lime juice until combined.  Stir in the flour and lime zest.  

Pour the mixture into the crust.  Bake for 40 to 50 minutes or until the center is firm.  Allow the tart to cool completely in the pan on a wire cooking rack.  When the tart has cooled, release it from the springform pan and transfer to a serving dish.

For the topping, pour the cream into a large bowl of a standing mixer and beat on high speed.  When the cream becomes frothy, add the powdered sugar and vanilla.  Continue to beat until soft peaks form.  Do not overbeat. 

To serve, top the tart with a layer of the whipped cream mixture and garnish with strips of lemon and lime zest, if desired.  

Recipe tip:

To save time, calories, and fat, substitute a store-bought reduced-fat graham cracker crust.