The answer might surprise you.
I am a native Floridian, which means I grew up in a very weird (but wonderful) state and have a lot of thoughts on Key lime pie. There are a lot of ways to make this deceptively simple dessert. At its most basic, Key lime pie has a filling made with sweetened condensed milk, lime juice, and egg yolks, that is baked in a press-in cookie crust. I prefer the buttery flavor and crunchy texture of a classic graham cracker crust, but some people opt for crusts made with crushed shortbread cookies or vanilla wafers, or even cookies mixed with nuts. Some people also use chocolate wafers. Those people are wrong.
You can top your Key lime pie with mounds of fluffy whipped cream or sticky peaks of meringue to cut the intensity of the tart-sweet filling, but it’s also good without, especially if you like your citrus desserts a bit puckery.
My ideal Key lime pie has a graham cracker crust, creamy and tart-but-not-too-tart filling, and swirls of burnished meringue on top. But I’ll gladly eat this classic dessert in other forms—as long as it doesn’t contain one thing: lime juice. Persian lime juice, that is.
WATCH: Key Lime Gimlet
Persian limes are the golf ball-sized bright green limes you’ll find in bins at your supermarket, usually next to the lemons. They make a fine lime pie, but that’s not what we’re talking about here. We’re talking about Key lime pie (note the capital ‘K’), which is made with Key limes, tiny little limes that are greenish-yellow in color and completely different in flavor—brighter, tangier, and more floral than regular limes. Because they are smaller in size, it takes a lot of Key limes to produce enough fresh juice for a pie. You can buy bottled Key lime juice (I like Nellie & Joe’s Famous Key West Lime Juice or Manhattan Key Lime Juice) or get a good arm workout squeezing every drop out of those little suckers. Either way will give you that authentic Key lime pie flavor and color.
Speaking of color, a Key lime pie is pale yellow. Save the green food coloring for St. Patrick’s Day.