Preheat oven to 350 degrees.
In a medium mixing bowl, combine the graham cracker crumbs and the melted butter. Mix until well combined.
Press mixture into a 9-inch pie plate and bake until the crust is set, about 10 minutes. Set aside to cool for a few minutes, but leave oven on.
In a large mixing bowl, combine the egg yolks, whole egg, condensed milk, lime juice and lime zest.
Pour the key lime filling into the cooled crust. Return to oven and bake until set, about 14 minutes.
Remove from oven and let cool completely on wire rack for 1 hour.
Refrigerate until completely chilled, about two hours.
Before serving, mix together the ingredients for homemade whipped cream above. Then, spread over cooled key lime pie and top with lime zest and fresh lime slices!
