1 1/2 cups crushed graham crackers (crush about 24 squares with a rolling pin in a sealed ziploc bag)
5 tablespoons melted unsalted butter
1/3 cup sugar
3 egg yolks
2 teaspoons key lime zest (rind of the lime, grated off with a fine grater)
1 (14-ounce) can sweetened condensed milk
2/3 cup freshly squeezed Key Lime juice
Preheat the oven to 350 degrees F (177 C)
Stir the melted butter into the crushed graham cracker crumbs and sugar until well combined. Press the mixture into the bottom and side of a pretty 9″ pie pan, making a neat edge around the rim of the pan. Bake in the center of your preheated oven 8-10 minutes. Set aside to cool on a rack and leave the oven at 350 degrees.
Meanwhile, in an electric mixer with the wire whisk attachment, beat the egg yolks and lime zest at high speed until very fluffy, about 5 minutes. Gradually add the condensed milk and continue to beat until thick, 3 or 4 minutes longer. Lower the mixer speed and slowly add the lime juice, mixing just until combined, no longer. Pour the mixture into the crust. Bake for 10 minutes, or until the filling has just set. Cool on a wire rack, then refrigerate. Freeze for 15 to 20 minutes before serving.
You can also make this in a tart pan, as I have done below, and use regular limes as Key Limes do not appear to be available in Australia!
Adapted from The Food Network