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Our Best Ever Key Lime Pie has the perfect blend of tart and sweet lime custard in a graham cracker crust.
My husband Jack and I have shared an obsession for Key Lime Pie ever since our early days of dating.
One year, because of work schedules, neither of us could travel to see family for the Thanksgiving holiday. So instead, we decided to both volunteer to help cook and serve Thanksgiving dinner at a local church homeless shelter. One of the nearby restaurants donated key lime pies for dessert – and they were the truly best key lime pies we’ve ever had!
Fast forward to today – Jack and I both still dream about those pies! Finally, we recreated our own version of the Best Ever Key Lime Pie – and we’re sharing it with all of you today.
What are key limes?
Key limes are smaller limes than the typical Persian limes you’ll find at the supermarket. Key limes sometimes have a reputation for being very tart – but when perfectly ripe, key limes are actually less tart with a distinctive flavor.
Key limes originated in the Florida Keys – which is where the name comes from. Today, however, most key limes sold at the supermarket are grown in Mexico because hurricanes and crop diseases have harmed most of Florida’s commercial key lime crops.
They are best during the summer into early fall months, and you should look for bags of key limes that are slightly yellow in color but still somewhat green.
If your key limes are all-green and hard – they aren’t ripe yet and you’ll struggle to get much juice from them. And, if your key lime is all-yellow – they are fully-ripe but will have a very bitter taste.
Choose key limes for this pie that are a yellowish green in color (as you see in our photos), and they should feel firm but not hard if you gently squeeze them.
The juice from a key lime is actually yellow – so a Key Lime Pie made with real key lime juice will be yellow. You can buy bottled key lime juice on-line here, but pies made with fresh juice really are the best. (We squeezed our limes with a citrus squeezer like this.
Key Lime Pie Origins
According to Andrew Zimmern (on his show Bizarre Foods America), a version of Key Lime Pie originated in the 19th century when Spanish sailors found small key limes growing in the Florida Keys. Their boats did not have stoves or refrigerators, so they mixed sweetened condensed milk with eggs and the key lime juice – then ate the concoction as a treat right on the boat.
Others say that a cook named Aunt Sally invented the pie for her boss – Florida millionaire William Curry – in the mid 1800’s. Her version baked the pie in a crust, then chilled in the ice box before serving.
Still others say that Key Lime Pie was created in the Borden Company test kitchen around 1931, as a way to sell more of their canned sweetened condensed milk.
No matter who created the Key Lime Pie recipe…we’re so glad they did!
Whipped Cream or Meringue Topping?
Key Lime Pie is sometimes served with whipped cream on top or on the side. Others insist that a meringue topping – similar to a Lemon Meringue Pie – is the best option. (Our vote is for a simple whipped cream so the lime custard flavors really shine through.)
Key ingredients and Substitutions
- Key limes – Absolute necessity for the authentic key lime flavor, and you should not substitute the larger Persian limes. You can find bottled Key Lime juice on line here if you can’t find fresh key limes. Choose key limes that are green with a slight yellow tint.
- Sweetened condensed milk – This thick and sweetened milk perfectly complements the tart lime juice and also adds a creamy texture to the finished pie.
- Egg yolks – Egg yolks are an essential ingredient to thicken this custard-like pie.
- Graham cracker crust – Back in the 1800s, a shortbread crust was used. Today, the most common crust for this pie is made with graham cracker crumbs, butter and sugar.
Special supplies needed
- A stand or hand mixer is needed to whisk the yolks before adding the other ingredients.
- Citrus juicer
- We baked our pie in a 10” deep dish pie plate. If you use a 9” pie plate, you will need to cut back on the filling.
How do I make Key Lime Pie?
- Make the crust by mixing graham cracker crumbs with brown sugar and melted butter, then bake until firm.
- Zest and squeeze limes. Zest your Key limes first (you’ll use it in the filling and for garnish), then squeeze the juice. This pie uses approximately 16-18 Key limes (which yields 10 tablespoons of key lime juice).
- Beat egg yolks until pale in color.
- Add sweetened condensed milk then whisk together
- Add the squeezed Key lime juice and zest. Whisk again.
- Pour the custard into the prebaked crust and bake until set
- Chill the pie overnight. Decorate with sweetened whipped cream and garnish with Key lime zest before serving in slices.
Chef’s Tip –
Before cutting our pie, we found it helpful to carefully set the chilled pie into a shallow pan (larger than the pie plate) filled with a little hot tap water. (Don’t let any of the water go over the rim into the pie.) Let it sit for 30 seconds – this will loosen the crust from the bottom and sides so it can be easily sliced and served.
Frequently asked Questions
- Why is my Key lime pie bitter? You likely used limes that were either too ripe or not ripe enough, or you substituted the larger Persian limes. Choose Key limes that are yellowish green in color.
- Can I make Key lime pie ahead? Yes – you can bake the pie, let cool, then chill for a few days before topping with whipped cream for serving.
- How do I store my pie? Key lime pie should be stored refrigerated. Place toothpicks in the pie to prevent the plastic wrap from sticking to the top of the filling if you’d like.
You may enjoy these other key lime recipes:
- Key Lime Torte
- Sweet and Sour Key Lime Pork
- Key Lime Ice Cream with Graham Cracker Pistachio Crumb Topping
- 30+ Fantastic Key Lime Recipes
2 sleeves graham crackers (18 crackers)
½ cup brown sugar
1/8 teaspoon salt
10 tablespoons melted butter (1 stick plus 2 tablespoons)
8 large egg yolks
2 tablespoons Key lime zest
10 tablespoons Key lime juice (approximately 16–18 key limes)
2 14-ounce cans sweetened condensed milk
1 ½ cups heavy cream
½ cup confectioners’ sugar
Additional Key lime zest or Key lime slices, for garnish
This pie will fit into a 10” deep dish pie plate.
Preheat oven to 350 degrees F.
Place the graham crackers into a food processor and process to crumbs.
Add brown sugar and salt and process for a few seconds to incorporate.
Add melted butter and process long enough to blend the butter into the crumb mixture.
Press the mixture into the bottom and up the sides of a 10” pie plate.
Bake for 15 minutes then cool while you make the filling.
In the bowl of a stand mixer with the whisk attachment, beat egg yolks for three minutes on medium high until they are pale in color and look creamy.
Zest the Key limes before squeezing the juice and add the zest to the eggs and mix.
Squeeze the juice and add to the bowl along with the sweetened condensed milk and whisk to incorporate all ingredients, scraping the bowl once or twice to make sure everything is blended.
Pour into the baked pie shell and place back in the oven for 15 minutes. The pie sets up quickly when baked and will seem firm and not runny when it is done.
Cool to room temperature then refrigerate overnight.
When ready to serve, whip the heavy cream to soft peaks then add the powdered sugar and then beat to stiff peaks.
Place whipped cream into a piping bag with a star tip and decorate as you will.
Sprinkle on Key lime zest or Key Lime slices before cutting and serving.
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