Easy Key Lime Cookies

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I merely have to whisper the words "key lime" and my husband will come running to the kitchen. Eric, is not much of a dessert eater, but as with any rule, there are exceptions. At a restaurant, he'll only order dessert if key lime pie is offered. No matter how many courses he has gone through, he'll always find room in his stomach for the citrusy custard in a graham cracker crust...leaving little to none for the rest of us. Fortunately, one batch of these Key Lime Cookies yields a generous 3 dozen, meaning that I get to grab at least a few before they are all devoured.

Four glazed key lime cookies on a wire rack.

Why you will love these Key Lime Cookies

Quick and easy: This is a basic cookie dough method, meaning that you whisk the dry ingredients, beat the butter with the sugar(s) and flavorings, and then mix them all together.....start to finish in less than 30 minutes. Even if you're not an experienced baker, trust me, you've got this!!
Graham cracker crumbs in the dough!: As mentioned above, the inspiration for this recipe is the always-popular key lime pie. I love my pie with a graham cracker crust, so I've incorporated graham cracker crumbs into the cookie dough to mimic its flavor.
A double dose of key lime: Both the buttery cookie dough and the glaze feature key lime zest and key lime juice, ensuring that you get the perfect tart/sweet combination in every bite.

Four key lime cookies stacked on a wire cooling rack.

Watch this quick video to see my cookies in action

Ingredients

All-purpose flour: Substitute a reputable gluten-free flour blend to make these cookies gluten-free.
Graham cracker crumbs: You can usually find graham cracker crumbs in the baking section of your grocery store, near the pre-made graham cracker pie crusts. You can also crush whole graham crackers using a zip-top bag and a rolling pin, or in a food processor. You should need 5-6 whole graham crackers to yield ⅔ cup crushed.
Unsalted butter: The butter needs to be at room temperature so it blends easily into the batter. See the Frequently Asked Questions section, below, for my favorite way to soften butter quickly if you don't have time to let it sit for hours to soften.
Eggs: Like the butter, eggs need to be at room temperature. To quickly do this, run them under warm water for a few minutes or soak them in a bowl of warm (not hot) water.
Key limes: If key limes aren't readily available in your grocery store, you can substitute equal amounts of regular lime zest and juice.
Half-and-half: Cream or milk may be substituted.
Pure vanilla extract: I try to avoid imitation vanilla whenever possible, as the resulting flavor is never as authentic as pure vanilla extract.

Equipment

Parchment paper: A good way to prevent cookies from over-browning on the bottoms or from sticking to the baking sheet is to use parchment paper as a liner. If you don't have parchment paper, Silpat silicone baking mats are a good substitute. You can also grease the pans with butter or non-stick baking spray, although these sometimes leave a film or cause bottoms of cookies to over-brown.
Electric mixer: Either a stand mixer or a hand mixer will work fine for this recipe. I do not recommend stirring this dough by hand, as it is on the thicker side.
Baking sheets: This recipe will fill up three baking sheets, but you can bake the cookies in batches if you only want to use one or two.

Step-by-step photos and instructions

Butter, sugars, zest, juice, vanilla and eggs mixed in a bowl.

Key Lime Cookie Dough

Preheat your oven to 375F. Line two baking sheets with parchment paper (see Notes.)
In a medium bowl, whisk flour, baking powder, baking soda, salt and graham cracker crumbs.
Using an electric mixer, beat the butter and both sugars at medium speed until light and fluffy, about 3 minutes. Add the eggs, one at a time, beating until incorporated. Beat in the zest, juice and vanilla.
On low speed, add the flour mixture in three additions, mixing until fully incorporated. Mixture will be slightly crumbly.

Dough for cookies rolled on a baking sheet.

Baked cookies cooling on a baking sheet.

5. Scoop heaping tablespoon portions of the dough and roll them into balls. Place the balls on the prepared baking sheets, spacing 2 inches apart.

6. Bake the cookies for 10-12 minutes, until the tops are puffed and cracked, and the edges are set. Cool on the baking sheets for 5 minutes, and then transfer the cookies to wire racks to cool completely.

Baked and iced cookies on a baking sheet.

Key Lime Glaze

In a medium bowl, whisk the confectioner's sugar, zest, half and half, salt and 3 tablespoons of the lime juice until smooth. Add more juice if necessary to get a thick but pourable glaze (or if you like an extra tart flavor!)
Using a spoon or an offset spatula, spread the glaze on top of the cooled cookies. Sprinkle with extra graham cracker crumbs and let glaze set 5 minutes before serving.

Frequently asked questions about Key Lime Cookies

What's the difference between a key lime and a regular lime?

The first thing that you are likely to notice about a key lime is that it is much smaller than a standard lime, usually weighing in at about 1 ounce per lime. As a result, it takes more key limes to produce the same amount of juice as regular limes. The flavor of key limes is also different in that it is less acidic, making them a popular choice in both baking and crafting cocktails.

Can I use regular limes juice in place of key limes?

Yes! If key limes aren't readily available, then you can use equal amounts of regular lime zest and juice in this recipe. Bottled key lime juice can be found in most grocery stores, next to the bottled lemon juice and regular lime juice.

How many key limes does it take to get 1 cup of juice?

A key lime contains anywhere from ½ to ⅓ as much juice as a standard lime. You can expect to get about 1 tablespoon of juice from a key lime, whereas a regular lime usually yields 2-3 tablespoons. So it would take about 16 key limes to get 1 cup of juice, vs 6-8 regular limes.

What's a quick and easy way to soften butter?

Depending on the temperature of your kitchen, it could take hours to soften butter. An easy alternative is to fill a tall glass with the hottest tap water (or boiling water.) Unwrap the stick of butter and stand it on a plate. Dump out the hot water and invert the hot glass over the stick of butter. After 4-5 minutes, you should have softened butter, ready to add to a recipe or spread onto toast! See video below for a demonstration.

Stack of four key lime cookies next to a glass of milk.

Love citrus flavors in your recipes? Here are a few more of my favorites:

Psst.... Did you try this recipe and enjoy it?? Let me know by giving it a rating or posting a comment. I love hearing from you!