My thumbprint-style key lime cookies feature a buttery, graham cracker crumb-based cookie with a tart key lime filling. They taste like mini key lime pies! Recipe includes a how-to video!
Why You’ll Love My Key Lime Cookies
- All the flavors of key lime pie without the wait! No waiting hours for it to firm up in the fridge.
- Can be made with bottled or fresh key lime juice. There’s no need to search high and low for real key limes if they aren’t easily accessible to you!
- Simple & fuss-free. My technique of shaping the dough BEFORE chilling means these cookies are easy to roll and hold their shape in the oven. So often thumbprint cookies will spread and lose their shape, but not these!
- Just so cute! These cookies make the perfect bite-sized dessert for summer parties or cookouts.
These cookies are based off of my popular thumbprint cookies, but today we’re using a tart key lime filling instead of jam. We’ll also incorporate some graham cracker crumbs into the cookie dough itself for even more flavor (and key lime pie vibes!).
What You Need
Most of these ingredients should be familiar to you, but I will review a few before we dig in.
- Key lime juice. It’s important to use key lime juice and not regular lime juice when making your filling, otherwise the flavor won’t be quite right. You can use fresh-squeezed or bottled juice (I like Nellie & Joe’s Key West Lime Juice!). However, for the zest you can get away with using either regular lime zest or key lime zest.
- White chocolate chips. These will help form the base for our filling. I recommend you stick with a higher quality brand (like Ghiradelli) for the best results.
- Graham cracker crumbs. These are an essential addition for a key lime feel, we’ll mix them into the cookie dough where they’ll add a subtle but present flavor.
- Sweetened condensed milk. Make sure you use sweetened condensed milk and not evaporated milk, as they will not work the same. Unfortunately they are sold right next to each other, so it can be easy to make the mistake of grabbing the wrong one. You will have some leftover condensed milk after making the filling; feel free to make dulce de leche or use it as a coffee creamer.
- Cornstarch. Cornstarch helps our cookie dough hold its thumbprint shape and prevents the cookies from spreading too much in the oven.
SAM’S TIP: Chilling the dough is important, especially if you make your key lime cookies on a hot summer day. However, make sure that you roll and indent your cookies before chilling the dough. This method prevents cracks from forming in your cookies (since the dough is more pliable!). After the cookies have baked, re-indent them with the back of a teaspoon.
Remember, this is just an overview of the ingredients I used and why. For the full recipe please scroll down to the bottom of the post!
How to Make Key Lime Cookies
- Make the dough – cream the butter and sugars together until smooth and combined, then stir in the egg yolk and vanilla. Gradually add the dry ingredients until you have a cohesive dough.
- Form the cookies – scoop and roll 2-teaspoon sized dough balls between your palms. It’s important to make sure these are smooth with no cracks, otherwise your cookies could crack in the oven! Press your thumb (or the back of a teaspoon) into each dough ball, then place in the freezer to chill.
- Bake and let cool completely before adding your filling. If the centers of your cookies puff up in the oven, use a rounded teaspoon to re-indent each cookie right after removing them from the oven. I do this with my chocolate thumbprint cookies too!
- Add the filling – Cook the white chocolate chips, condensed milk, and lime juice over low or medium-low heat until melted, then stir in the lime zest. Don’t crank up the heat, or you could end up burning your white chocolate. Spoon the filling into your cookies and let cool completely before enjoying.
SAM’S TIP: If your key lime cookies turn out dry and crumbly, there’s a pretty good chance you over-measured your flour. I have a whole post on how to measure flour, if you’ve run into this issue before I’d definitely recommend checking that out.
Frequently Asked Questions
These cookies can be kept at room temperature for up to 2 days. If you want to keep them longer than that, you will need to refrigerate them in an airtight container. Note that the filling usually stays a bit tacky even once it’s completely cooled, so these key lime cookies aren’t great for stacking.
Yes! Just make sure to store them in an airtight container with parchment paper in between the layers. I’d recommend you enjoy them within a few months for the best flavor and texture.
I use the white chocolate in this recipe to create the proper filling texture (not for the flavor). However, I don’t want to say you can’t taste it at all. It’s a very subtle taste, but if you absolutely can’t stand white chocolate, you might not be a fan of this recipe.
Several readers have tried substituting the lime juice/zest with lemon with great success! 🍋
If you’re looking for more fun twists on classic key lime (or more ways to use up a bottle of key lime juice), check out my key lime pie cake or key lime cheesecake next.
Enjoy!
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Key Lime Cookies
Ingredients
Cookies
- 1 cup unsalted butter softened
- ⅓ cup (70 g) sugar
- ⅓ cup (67 g) light brown sugar tightly packed
- 1 large egg yolk
- 1 teaspoon vanilla extract
- 2 cups (250 g) all-purpose flour
- ½ cup (65 g) graham cracker crumbs
- 2 teaspoons cornstarch
- ½ teaspoon salt
Key Lime Filling
- 1 cup (170 g) good quality white chocolate chips
- ½ cup (170 g) sweetened condensed milk
- 3 Tablespoons key lime juice
- 2 teaspoons lime zest key limes are expensive, I just used zest from a regular lime
Instructions
- Combine butter and sugars in the bowl of a stand mixer (or use a large bowl and an electric hand mixer) and beat until well-creamed.1 cup unsalted butter, ⅓ cup (70 g) sugar, ⅓ cup (67 g) light brown sugar
- With mixer on low, stir in egg yolk and vanilla extract, pausing to scrape down the sides and mixing until ingredients are well-combined.1 large egg yolk, 1 teaspoon vanilla extract
- In a separate bowl, whisk together flour, graham cracker crumbs, cornstarch, and salt.2 cups (250 g) all-purpose flour, ½ cup (65 g) graham cracker crumbs, 2 teaspoons cornstarch, ½ teaspoon salt
- Gradually add the flour mixture to your wet ingredients, being sure to scrape the sides and bottom of the bowl so that all ingredients are well-combined.
- Scoop cookie dough into 2-teaspoon-sized balls and roll until smooth (so that the dough is round and there are no cracks/seams in the cookie dough — this will help keep your thumbprints from cracking).
- Use your thumb or the rounded back of a teaspoon to gently press an indent in the center of the cookie dough. Repeat until all of the dough has been used.
- Chill imprinted dough in freezer for 30 minutes.
- Preheat oven to 350F (175C) and line cookie sheets with parchment paper (if using. An ungreased, non-stick cookie sheet will also work).
- Place chilled cookie dough on sheet spacing at least 1″ apart.
- Bake on 350F (175C) for 10-11 minutes and allow to cool completely on pan. Wait for cookies to cool completely before preparing filling.
Key Lime Filling
- In a small saucepan over medium-low heat, combine white chocolate chips, condensed milk, and key lime juice.1 cup (170 g) good quality white chocolate chips, ½ cup (170 g) sweetened condensed milk, 3 Tablespoons key lime juice
- Stir frequently until chocolate is melted and ingredients are well-combined. Stir in lime zest and stir until mixture just begins to bubble.2 teaspoons lime zest
- Reduce heat to low and spoon filling into thumbprints of cookies (I use a 1-tsp sized cookie scoop, it makes the process much easier and less messy!).
- Allow to cool completely before serving (filling may still be a little tacky to touch, even when cooled completely. This is normal).
Nutrition
Nutritional information is based on third-party calculations and should be considered an estimate only. Actual nutritional content will vary based upon brands used, measuring methods, cooking method, portion sizes, and more.
This key lime cookie recipe was originally published 06/06/2018, post updated 05/13/2019
Anna K
Can I make the dough ahead of time and leave it in the fridge overnight?
Sam Merritt
Hi Anna! That will work just fine. I would refrigerate after making the thumbprint in the cookies. 🙂
Anna K
Perfect thanks! I will leave a review after I bake them!