Guess what. This wasn't made with key limes. Guess what else. It wasn't made with fingernails, either.
Adapted from The Joy of Cooking
1 packet of graham crackers (about 1 ½ cups of crumbs)
½ cup vanilla sugar
¾ stick butter, melted
½ teaspoon kosher salt
1 14 oz tin of sweetened condensed milk
4 large egg yolks, room temperature
½ cup lime juice (Or just over: I top mine off with the juice from half a meyer lemon)
2 tablespoons vanilla sugar
¼ teaspoon kosher salt
Zest from one lime
1 cup cold, fresh heavy cream
¼ cup vanilla sugar, depending on taste
Preheat oven to 350° F.
Crush graham crackers inside a Ziploc bag or food processor until even, pebbly small crumbs commence. Pour into a bowl, add salt and vanilla sugar and mix with melted butter until moist. Press into the bottom and sides of a 9 inch springform pan and bake for 10-12 minutes, until edges are golden brown and crisp. Remove and cool completely.
Turn down oven to 325 degrees. Meanwhile, whisk the sweetened condensed milk, lime zest, vanilla sugar, salt and egg yolks together until well combined. Add the lime juice, whisking quickly, until the mixture is smooth and liquid. Pour into cooled crust and bake for 16 minutes, checking after 14 – pie should have no color, should look set but quiver slightly when pan is pushed or set down. Like the face of a paunchy, frightened 37 year old who lives in his mother's basement. Remove from oven and cool, on rack, completely. Chill for at least five hours before serving. I'm serious. Chill.
To serve, whip cream and vanilla sugar in a chilled bowl until voluminous, slightly stiff peaks form. Spread lightly in the center of the pie, dash with another bit of lime zest, and serve.