How To Make Key Lime Pie

Master the art of the tart pie crowned with fluffy meringue

Sorry, lemon meringue. Our sincere apologies, banana cream. If we had to pick our favorite custard pie, we'd have to go with Key lime, the creamy, tropical pie from the tip of Florida that puts other custard pies to shame.

There's the graham cracker crust. The rich, tart filling of Key lime juice mixed with sweetened condensed milk and egg yolks. And ours is topped with a fluffy meringue that we torch to golden perfection (see the recipe).

While to non-Floridians Key lime pie is just a sweet treat, to natives of Key West, the pie is more meaningful. Kermit Carpenter, owner of Kermit's Key West Key Lime Shoppe, grew up making fresh Key lime pie with his grandmother in the 50s. It brought him so much joy that he began making and selling Key lime pies (with her recipe, of course) 25 years ago—and his shop is still thriving.

Luckily for us, Carpenter and other Key lime masters share their tips for a Key West grandmother-approved slice of pie.

Crust is a must. "I think a good graham crust is buttery, just sweet enough, slightly caramelized, slightly gooey (with Key lime in this case) and a little salty at the end," Ron Silver, chef/owner of Bubby's in NYC, says. Silver even goes so far as to make his own graham crackers.

While we applaud Silver, we're realistic (and very busy), so we simply crush store-bought graham crackers and mix them with a little butter, sugar and salt. The real trick to a good graham cracker crust is the amount of butter you use. You want the crumbs wet, but too much butter will cause the crust to slide down the sides of the pan while baking.

Get fresh. With only a few ingredients (our filling has five), you've gotta be careful with what you put in there. "From my perspective, it's all about the ingredients in terms of quality and freshness," Steve Tarpin, owner of Steve's Authentic Key Lime Pies in Brooklyn, New York, explains. "In that regard, no premade crust, no bottled 'mystery juice' from concentrates, and the freshest sweetened and condensed milk possible."

The "mystery juice" Tarpin is referring to is Key lime juice concentrate, which often is just Persian lime (the typical lime you have in your fridge) juice mixed with preservatives and bottled in Key West. Fresh Key lime juice is tarter than a Persian lime with a bright floral flavor.

"I always recommend that people making a Key lime pie from scratch use fresh-squeezed Persian limes if Key limes aren't available," Tarpin adds. In other words: Put. the. bottle. down.

Can you dig it? Canned sweetened condensed milk is non-negotiable, the reason being that fresh dairy didn't come to the Keys until long past the creation of this pie. The thick condensed milk reacts with the acidity in the lime juice, thickening into a custard in the oven with the help of egg yolks.

Carpenter recommends blending the egg yolks and condensed milk well before adding the juice to prevent lumps, since the juice starts working the moment it hits the other ingredients.

Carrying the torch. Though most top their pies with fresh whipped cream, we go with a meringue. It's partly as an homage to the history of the dish and its lack of dairy, but it's also an easy way to use up leftover egg whites from the filling.

See? It's a piece of cake pie.