Gluten-Free Key Lime Pie (with Lime Sugar & Whipped Cream)

A photo of slices of key lime pie in a pie tin.

This gluten-free key lime pie has a buttery graham cracker crust, a creamy and tart custard filling, and a generous layer of piped whipped cream on top. The filling is naturally gluten-free, and with store-bought gluten-free graham crackers for the crust, the whole pie comes together easily.

What sets this version apart is the lime sugar. Before the pie chills, you rub fresh key lime zest into granulated sugar and sprinkle it over the warm filling. It adds a bright, fragrant layer of citrus flavor right on the surface that you taste in every bite.

Why You’ll Love This Recipe

The filling is naturally gluten-free. Classic key lime pie filling is just egg yolks, sweetened condensed milk, and key lime juice, so no substitutions or workarounds are needed. The only gluten-free swap is the graham cracker crust.
Lime sugar takes it over the top. A sprinkle of key lime zest rubbed into sugar goes onto the warm filling before it chills. It creates a subtle, aromatic layer of citrus that most key lime pie recipes skip entirely.
It looks impressive with minimal effort. The custard filling comes together in one bowl, the crust is a simple press-in, and piping the whipped cream with a star tip gives the finished pie a polished, bakery-style presentation.

Ingredients

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Ingredient Notes

Gluten-free graham crackers – I use Kinnikinnick Gluten-Free S’moreables Graham Crackers for this crust. You’ll need about half a box to get 1 cup of crumbs. You can also make your own homemade gluten-free graham crackers for an even fresher flavor. For a more detailed walkthrough of the crust itself, check out my gluten-free graham cracker crust recipe.
Key Limes – Key limes are smaller and less acidic than regular (Persian) limes, with a slightly floral flavor. If you can’t find them, bottled key lime juice works well. I like Nellie and Joe’s Key West Lime Juice, which I find easily at my local grocery store.
Egg Yolks – The yolks create the custard-like texture of the filling. Depending on the eggs you use, your filling may look more yellow or more orange. Free-range and organic yolks tend to be darker, which is completely normal.
Sweetened Condensed Milk – This is not the same as evaporated milk. Sweetened condensed milk is thick and sticky and provides both the sweetness and body of the filling. One 14-ounce can is all you need.

How to Get a Graham Cracker Crust That Holds Together

The key to a crust that slices cleanly is pressing the crumbs firmly and evenly into the pie pan. Use the flat bottom of a measuring cup to compact the crumbs across the bottom and then work your way up the sides. Bake the crust for 10 to 12 minutes at 350°F until it’s golden and fragrant, then let it cool before adding the filling. A well-pressed, fully baked crust won’t crumble when you cut into the pie.

A piece of key lime pie with graham cracker crust being lifted out of a pie tin with a spatula.

Expert Tips

Press the crust with a measuring cup. Using the flat bottom of a dry measuring cup gives you a more even, compact layer than pressing with your fingers. Work the bottom first, then press the crumbs up the sides of the pie pan.
Don’t overbake the filling. The edges of the pie should be set, but the center will still be slightly wobbly when you pull it from the oven. It will finish setting as it chills in the refrigerator.
Wait to add the whipped cream. Homemade whipped cream softens within a few hours, so pipe or dollop it on right before serving for the best texture and presentation.

Recipe FAQs

Are key limes and regular limes different?

Key limes are smaller, rounder, and more yellow-green than regular Persian limes. They have a more tart, slightly floral flavor that is less acidic than Persian limes. Key limes also have thinner skin and more seeds. The flavor difference is noticeable in a pie, but both types work well in this recipe.

Can I use regular limes instead of key limes?

Yes. Regular (Persian) limes will work in this recipe. The flavor will be a bit sharper and less floral than key limes, but the pie will still taste great. Use the same amount of juice called for in the recipe.

Does the pie pan size matter?

I use a 9-inch pie plate that is 1 inch high. An 8-inch pan will give you too much crust and too much filling. A 10-inch pan won’t have enough filling to set properly, so you would need to increase the recipe by about 1.5 times.

A close-up of a fork breaking off a bite of key lime pie.

Room Temperature

Key lime pie should not be left at room temperature for more than 2 hours since the filling contains egg yolks and dairy. After baking, let the pie cool at room temperature for about 30 minutes before adding the lime sugar and transferring it to the refrigerator.

Refrigerator

Store the pie covered in the refrigerator for up to 3 to 4 days. Keep the whipped cream off until you’re ready to serve, since homemade whipped cream loses its shape over time. Cover the pie loosely with plastic wrap or place it in an airtight container to prevent it from absorbing other fridge odors.

Freezer

This pie freezes well for up to 2 months. Freeze it without the whipped cream. Let the pie chill completely in the refrigerator first, then wrap it tightly in plastic wrap followed by a layer of aluminum foil. To serve, thaw the pie in the refrigerator overnight and add whipped cream just before slicing.

Serving Suggestions

Key lime pie pairs well with a citrus-themed dessert spread if you’re serving a crowd. Set it alongside a batch of gluten-free lemon bars for guests who love that sweet and tart combination, or add a bowl of lemon sorbet as a lighter, dairy-free option on a hot day. If you’re putting out multiple pies, a gluten-free strawberry cream cheese pie gives you a fruity contrast to the tangy citrus filling of the key lime.