These key lime sandwich cookies have a thick filling of sweet and zesty key lime buttercream sandwiched between two soft and chewy graham-flavored cookies. It’s everything you love about a classic key lime pie, reimagined into a cookie!
These key lime sandwich cookies turn a slice of my favorite pie into a cookie! They have soft, buttery cookies flavored with graham cracker crumbs filled with zesty key lime buttercream that’s tart and creamy all at once. Bite into one, and you’re hit with the perfect mix of chewy cookie sweetness and bright, tangy lime.
Things to Love About These Key Lime Cookies
Key lime pie, to go. A slice of pie is tricky to tuck into a purse, but not a cookie! This recipe is the classic key lime pie experience reimagined as a portable cookie sandwich.
Bright key lime flavors. These cookies are like a mini vacation for your tastebuds. They’re packed with fresh and creamy lime filling that practically screams summer.
Easy recipe. If you can get your hands on key limes, the rest of the recipe is a breeze. The ingredients are simple and the key lime sandwich cookies are quick to assemble. I’ll walk you through it step by step.
Ingredients You’ll Need
Sandwich cookies are the best excuse to devour two cookies and a mound of frosting all in one! I based the graham cookies in this recipe on my s’mores cookies, and the ingredients couldn’t be easier. I’ve included some notes below. Scroll down to the printable recipe card after the post for the full list and amounts.
Butter – Brought to room temperature. I always bake with salted butter, but unsalted butter works, too.
Light Brown Sugar – You could also use granulated sugar or dark brown sugar.
Eggs and Vanilla – Real vanilla extract has the best flavor (compared to artificial vanilla). If you think of it, bring your eggs to room temperature ahead of time.
Graham Cracker Crumbs – You can buy ready-to-use graham cracker crumbs, or grind store-bought or homemade graham crackers into crumbs using a food processor.
Dry Ingredients – Flour, baking soda, and salt. I use all-purpose flour. Be sure to measure the flour correctly using a kitchen scale or the spoon and sweep method (spoon the flour into the measuring cup and level it off afterward).
For the Key Lime Buttercream Filling
Butter – Again at room temperature.
Key Limes – You’ll need the juice and zest from 1-2 limes (zest the limes before you juice them). Key limes are different from other limes, see below.
Powdered Sugar – Also called confectioner’s sugar or icing sugar.
Key Limes vs. Regular Limes
Most grocery store limes are Persian limes. Key limes are smaller and more aromatic, known for their distinct flavor that’s tart, but less acidic.
How to Make Key Lime Sandwich Cookies
Making homemade key lime sandwich cookies from scratch is easy as, well, pie! Follow the steps here, and scroll to the recipe card for the printable instructions.
Mix the wet ingredients.Add the graham cracker crumbs and leavening.
Mix the wet ingredients. Start by creaming softened butter with sugar until it’s light and fluffy, then add the eggs and vanilla.
Add the dry ingredients. Next, mix in the graham cracker crumbs, baking soda, and salt. Lastly, slowly add the flour until the dough is just combined.
Mix in the flour.Portion and bake the cookies.
Bake. Use a medium cookie scoop to drop spoonfuls of dough onto a baking sheet lined with parchment paper. Bake at 350ºF for 9-10 minutes. Afterward, cool the cookies on the pan for 2-3 minutes, then move them to a wire rack to cool completely before you add the frosting.
Make the key lime frosting.Fill the cookies.
Make the buttercream filling. Meanwhile, beat butter with lime zest, then slowly add the powdered sugar and key lime juice. Give the frosting a good final whip for 1-2 minutes until it’s fluffed and smooth.
Fill the cookies. Flip half of the cooled cookies upside down. Using a piping bag (or a zip-top bag with the corner snipped), pipe the key lime filling onto the bottom of the flipped cookies. Close the sandwiches with the other cookies, and enjoy!
Recipe Tips
Use a cookie scoop. This is the easiest way to portion out cookies that are the same size (which is key when making sandwich cookies!). Alternatively, you can weigh the cookie dough using a kitchen scale.
Reshape the cookies. If your cookies spread while baking or come out of the oven looking a little misshapen, use the edge of a glass or a spatula to gently press to cookies back into shape. The trick is to do this while they’re hot from the oven.
Don’t overbake. The graham cookies should be lightly golden at the edges and still a bit soft in the middle when they come out of the oven. Overbaking makes the cookies dry instead of soft-baked and chewy.
Scrape down the bowl. When making the buttercream filling, remember to occasionally scrape down the sides of the bowl with a spatula to ensure that everything is evenly mixed.
How to Store
At room temperature. Store these key lime pie sandwich cookies airtight at room temperature for up to 3 days.
Freeze. You can freeze the assembled sandwich cookies in an airtight container for up to 2 months. Thaw the cookies at room temperature.
More Sandwich Cookies Recipes
This recipe was originally published in 2017. The photos and helpful tips have been updated in 2025! Enjoy!
These key lime sandwich cookies are everything you love about a classic key lime pie, reimagined into a soft and chewy graham-flavored cookie filled with sweet and zesty key lime buttercream.
Graham Cookies
1 cup butter, room temperature
1 1/2 cups light brown sugar
2 large eggs
2 teaspoons vanilla extract
2 cups graham cracker crumbs
1 teaspoon baking soda
1 teaspoon kosher salt
2 cups all-purpose flour
Key Lime Buttercream Filling
1/2 cup butter, room temperature
1 tablespoon lime zest
3 tablespoons freshly squeezed key lime juice
4 cups powdered sugar
Cookies: Preheat the oven to 350°F. Line a baking sheet with parchment paper and set aside.
In the bowl of your stand mixer, fitted with the paddle attachment, mix the butter and sugar on medium speed for 2 minutes until light and fluffy. Turn the speed down slightly and add in eggs and vanilla, mixing until smooth, scraping the sides of the bowl as necessary.
With the mixer on medium-low speed, add in the graham cracker crumbs, baking soda, and salt, mixing until incorporated.
Turn the mixer speed to low and slowly add in flour until just combined.
Using a medium (2-tablespoon) cookie scoop, drop the dough about 2 inches apart onto the prepared baking sheet.
Bake cookies for 9 – 10 minutes until the edges are lightly golden.
Remove from the oven and allow the cookies to cool on the pan for 2 – 3 minutes, then transfer to a wire rack to cool completely.
Buttercream Filling: While the cookies are cooling, prepare the filling. In the bowl of the stand mixer fitted with paddle attachment, mix butter and zest until combined and smooth. Turn the mixer to low and slowly add in powdered sugar and key lime juice. Mix until combined, then turn the mixer to medium and beat for 1 – 2 minutes until creamy and smooth, scraping the sides of the bowl as necessary.
Turn half of the cookies upside down. Fill a piping bag (or a zip-top bag with the corner cut off) with key lime filling and pipe on approximately 2 tablespoons onto the bottoms of half of the cookies. Place the other half of the cookies on top of the filling, creating sandwiches.
Notes
Store airtight for up to 3 days at room temperature for best freshness.
Freeze the baked and assembled cookies airtight for up to 2 months for the best freshness. Thaw at room temperature.
