A slight spin on a real classic, these Easy Key Lime Pie Bars will make all your Summer baking dreams come true with ease! The bars make for a deliciously transportable and handheld bite. Ideal for backyard BBQs, casual hosting or simply to eat after your midweek dinner for something a little exciting!

The base comprises of Graham Cracker crumbs, butter and sugar. If you are based in the UK or a country where Graham Crackers aren’t so easy to find, digestive biscuits or ginger nuts are a great substitute. The filling is then made using eggs, condensed milk and lots of lime juice. Once again, no fear if key limes aren’t easy to find near you – regular limes work just as well! Finally, we top with a fluffy whipped cream. No meringue here, unless you really want to – as I find cream just as wonderful and almost zero work!

The only equipment you really need is a square tin and some kind of whisk. Electric will make your life so much easier but these can be made with a balloon whisk and some elbow grease! The base gets baked prior to adding the filling, so leave the oven on whilst making the lime mixture. You will know that the bars are done from a light golden tint to the edges and minimal wobble (just a little is good!).

The Origins of Key Lime Pie

Region of Origin: Key lime pie originated in the Florida Keys, specifically Key West.
- Key Ingredient: It uses Key limes, a smaller, tarter variety of lime native to the Florida Keys.
Historical Roots:
- Believed to have been created in the late 1800s to early 1900s.
- The pie likely emerged due to the lack of refrigeration in the Keys at the time, which made sweetened condensed milk a staple for cooking.
Early Documentation:
- Recipes similar to Key lime pie appeared in Borden condensed milk promotional materials in the 1930s.
- A “Tropical Lime Chiffon Pie” appeared in a 1931 Miami Herald article, but without a crust.
Local Folklore:
- A popular (though unverified) story attributes the invention to Aunt Sally, a cook for Florida millionaire William Curry in the late 19th century.
Cultural Significance:
- Became widely popular in Florida and the southern U.S. over time.
Designated the official state pie of Florida in 2006.
Traditional Preparation:
- Typically made without baking; the acidity of lime juice chemically “cooks” the egg yolks.
- Modern versions are usually baked briefly for food safety.

Let me know if you’d like a deeper dive into any of these points!

INGREDIENTS REQUIRED

There are no specialist ingredients or equipment required for this bake. I can find everything I need at my local supermarket or grocery store. I use an 8″ square baking pan to bake these, lined with some greaseproof paper. These slice easily into 9 squares but could be cut further into diagonals for 18.

Graham Crackers (or Digestive Biscuits in the UK/Aus)
Unsalted Butter
Granulated Sugar
Egg Yolks
Sweetened Condensed Milk
Fresh Limes
Lime Juice (can either be the artificial kind or fresh)
Heavy Cream

Tips for Top Tier Easy Key Lime Pie Bars

Biscuit Base: Crush your graham crackers/biscuits to a fine sand like texture. You can do this in a food processor, blender or by hand with a rolling pin. The finer, the better it holds together.
Butter: Unsalted Butter is best here, unless you are a big salt/sweet fan! We melt it to make sure it mixes well with the crumbs.
Sugar: I opt for white granulated sugar. A light brown sugar would also be delicious if that’s what you have.
Filling: Use large eggs and separate before adding the yolks to the bowl to prevent any unwanted white from adding in. Sweetened condensed milk is required as no additional sugar is added to the mixture.
Whipped Cream: Home whipped or out of a can are both fine. If whisking yourself, do it in intervals. Stop the mixer regularly to scrape the sides of the bowl and to make sure you don’t over whisk!

Whilst I know it is super tempting to dive straight in, for the best filling you do need to let these chill in the fridge. This helps them to firm up. 2 hours is my minimum recommendation. This makes for a great bake-ahead item – letting sit in the fridge until ready to top with whipped cream and serve! (Don’t make the whipped cream too far ahead of time as it ‘hardens’ in the fridge).

For these Easy Key Lime Pie Bars I use a basic 8′ square pan (I like this one). I also recommend using an electric or stand mixer to really combine the filling (with a mixer like this). If you’re looking for another easy bake to share, try these Chocolate Chunk Cookie Bars. For videos and baking inspiration, head on over to my Instagram. If you make this recipe, don’t forget to drop it a star rating, leave a review or share a photo on your socials!

Storage for Easy Key Lime Pie Bars

Here’s how to properly store your Easy Key Lime Pie Bars to keep it fresh and safe to eat:

🧊 Refrigerator Storage (Short Term)

Cover the pie: Use plastic wrap, aluminum foil, or an airtight container to prevent drying out or absorbing odors.
Refrigerate immediately: After the pie has cooled, refrigerate within 2 hours of baking or assembling.
Shelf life: Lasts for 3 to 4 days in the fridge.

❄️ Freezer Storage (Long Term)

Freeze for longer storage:
Wrap the pie (or individual slices) tightly in plastic wrap and then in aluminum foil.
Store in an airtight freezer-safe container or zip-top bag for extra protection.
Shelf life: Can be frozen for up to 2 months.
Thawing: Defrost in the refrigerator overnight—don’t microwave or thaw at room temperature to maintain texture.

⚠️ Tips & Warnings

Do not leave out at room temperature for more than 2 hours (or 1 hour if above 90°F/32°C) due to the dairy and egg content.
Avoid soggy crust: If you’re making the pie ahead, consider storing the filling and crust separately, especially if using a graham cracker crust.