There’s something about lime that generates a special craving inside me. Limes are cool and tangy, full of flavor, providing a great contrast against added sweetness. Perfect partners, you might say. Key limes even more so have a beautiful aroma, unique taste, and are tiny, setting them distinctly apart from common Persian limes. Key limes (citrus aurantifolia) originated in Southeast Asia, were brought by traders to the Middle East and by Crusaders to Europe, and brought to the New World by explorers and conquistadors, making themselves at home in the ideal growing conditions of Mexico, the West Indies, and southern Florida.
In the late 1800’s, someone in Florida discovered a magical flavor combination by matching the tangy key lime together with sweetened condensed milk, and it is that result that has brought us together today. Note that traditional key lime pies were not baked, as the chemistry of the lime actually cooks the egg. If you’ve ever had ceviche, it’s the same chemistry concept at work, as in ceviche the lime cooks the fish. However, in this era of health concerns, we bake our pie. Just to be sure. Going back to the key lime pie tradition, there is argument as to whether it should be created with a pastry crust or with a graham cracker crust, and there is argument as to whether it should be topped with a meringue, or with fresh whipped cream. Instead of arguing, let’s get baking. ‘Tis better to eat than to argue. Just for the sake of clarity and full disclosure, we will be using a graham cracker crust and a fresh whipped cream topping.
1-1/2 cup graham crackers
4 Tbsp. granulated (or baker’s) sugar
1/2 cup (1 stick) melted butter
1/4 tsp. sea salt
4 egg yolks
1 can (14 ounces) sweetened condensed milk
3/4 cup fresh Key lime juice (for a very tangy pie! For less tang, lessen to 1/2 to 2/3 cup)
1 tsp. grated key lime zest
1 cup heavy whipping cream
3 Tbsp. confectioners’ (powdered) sugar
1/2 tsp. vanilla extract
I recommend your first step be to zest your limes, then squeeze them, as it is a bit time-consuming to squeeze the 30-40 key limes it takes to fill 3/4 of a cup (or 1/2 cup if you want less tanginess). Key lime pie is actually quite easy to make, so you might as well get the most time-consuming part out of the way first. I also recommend you use a small size Mexican lime juicer. They’re cheap and are made specifically for this purpose. Just cut the lime in half and place it in the juicer upside down and squeeze the handles together, just like a garlic press.
Preheat the oven to 375°. Break up the graham crackers in your hand and place them in a food processor, processing until they are mostly crumbs. Add the melted butter, sugar, and salt and pulse until combined. The mixture should be slightly clumpy yet still somewhat crumbly.
Press the mixture into the bottom of a 9-inch pie pan, forming an even layer covering the bottom, sides and edge. Bake the crust for 12 minutes. Remove from the oven and allow to cool while you mix the filling.
Lower oven temp to 325°. In a medium to large bowl whisk by hand (or use an electric mixer with the wire whisk attachment) the egg yolks and lime zest until thoroughly mixed and somewhat fluffy. Add the condensed milk and continue to whip until mixed and thick. Add the lime juice and whisk until fully incorporated. Pour the mixture into the cooled crust. Bake for 15 minutes, until the filling has just set. Remove from oven and allow to cool, then refrigerate for at least two hours (overnight is even better).
To make the topping: The easiest way is to use the whisk attachment on an electric mixer. You can do it by hand, but your arm will be pretty tired before you’re done. Whip the heavy whipping cream, confectioners’ sugar, and vanilla until nearly stiff and it starts to form peaks.