These low carb lemon bars have a buttery almond flour crust and a smooth, tangy filling I've tested more times than I can count. Around 3g net carbs per bar, and the crust holds up even after sitting in the fridge overnight.
I made these for a local fundraiser dessert auction a couple of years ago, and they ended up being the top-bid item of the entire event. Almond flour cookies, brownies, all of it. The next year, the same buyers came back asking if I brought 'those lemon bars' again. That's when I knew this recipe was permanent.
Each bar comes in at around 3g net carbs, which is part of why I reach for this recipe when I need a dessert that works for everyone at the table. The crust is almond flour with a sprinkle of unsweetened coconut flakes, and that combo gives you a buttery base with a real crunch that holds under the filling. Even if coconut isn't your thing, you'll barely notice it. It's there for texture, not flavor. I've made these without the coconut too, and the crust comes out softer, more like a sandy shortbread. Still works, but I prefer the version with them.
The filling is bright and tart without being sour. I use powdered sweetener (not granular) because it dissolves completely into the curd and gives you that smooth, clean texture. One tablespoon of arrowroot thickens the entire batch, and per bar, it adds less than a gram of carbs. If you've baked my pie crust, you already know almond flour bakes into something sturdy, and that same principle applies to this base.
I actually think these taste better the next day once the lemon curd has settled and chilled. You can assemble and bake them the night before without the crust getting soggy. The almond flour base doesn't absorb moisture the way regular shortbread does, which is one of the reasons I keep making them. Slice them cold out of the fridge and the cuts come out cleaner too.
These are a solid make-ahead keto dessert for parties, especially alongside something richer like chocolate mousse or peanut butter pie. If you're building a low carb dessert spread, pair them with s'mores or strawberry shortcake kebabs for contrast. Citrus next to chocolate is always a good call.
My tips for smooth, slice-worthy bars every time
I hate it when a recipe doesn’t work on the first try, so here are the tricks I rely on to make sure these come out bright, smooth, and slice-worthy from the start. These are the same tips I used when I made them for that fundraiser dessert auction, and when you’re the top-bid item, you take notes.
Use powdered sweetener, not granular. This is the single biggest difference between a smooth filling and a gritty one. Granular sweetener doesn’t fully dissolve in the curd, and you can feel it on your tongue. I’ve tested both multiple times. Powdered every time. If your sweetener is granular, pulse it in a blender for about 30 seconds and it dissolves like powdered.
Use fresh lemon juice when you can. You can use bottled in a pinch, but fresh-squeezed gives these their signature punchy flavor. It’s worth the extra minute to slice a few lemons.
Don’t worry about white bubbles on top. Those tiny bubbles after baking come from air in the eggs. They don’t affect flavor, and you can hide them with a light dusting of powdered sweetener once cooled.
Lift the whole slab out with parchment handles. Grease your baking dish first, then line it with parchment, leaving a couple of inches hanging over the sides. I think of them as little handles. They let you lift everything out in one clean piece, which makes cutting neat squares much easier.
Why I use arrowroot powder. Arrowroot is my go-to thickener here because you only need a tiny amount. It’s gluten free, grain free, and while it does contain carbs, one tablespoon thickens the entire curd. Per square, it adds less than a gram. If you don’t have arrowroot in your pantry, about a teaspoon of xanthan gum does the same job.
How I store and freeze these
Once you’ve sliced them into squares, keep them in an airtight container in the refrigerator. I actually think they taste better the next day after the filling has time to settle and chill, so they’re a great make-ahead dessert if you’re planning for a gathering.
They’ll stay fresh for 4 to 5 days in the fridge. For longer storage, you can freeze them for up to a month. Place parchment between the layers so they don’t stick together, then wrap the whole container tightly. When you’re ready to eat them, move them to the fridge the night before and let them thaw slowly. Thawing at room temperature can make the filling weep, so the fridge is the way to go. They’ll taste close to fresh after about 8 hours of slow thawing.
In a small bowl, combine all the ingredients for the crust and mix until combined.
For this step
1 ½ cups almond flour
1/4 cup sugar-free sweetener
1/2 cup coconut flakes, unsweetened
4 tablespoons (½ stick) melted unsalted butter
1/2 teaspoon salt
1 teaspoon lemon zest
3
Press into dish
Press into a greased, parchment lined square baking dish.
4
Bake it
Bake at 325°F for 10-12 minutes. Set aside to cool and increase the oven temperature to 350°F.
5
Lemon curd
To make the filling, mix the ingredients for the curd in a bowl.
For this step
4 eggs
1 ¼ cup powdered sugar-free sweetener
3/4 cup of lemon juice (if like it less tart, try 1/2 cup)
1 tablespoon arrowroot powder
1 teaspoon baking powder
pinch of salt
zest from one lemon
6
Pour the filling
Pour the mixture on top of cooled crust.
7
Bake it
Bake at 350°F for 20-25 minutes.
8
Final dusting
Dust with powdered sugar-free sweetener.
Nutrition
Per serving: 1 bar
Calories
138
Fat
11.6g
Protein
4.3g
Total carbs
4.1g
Net carbs
2.9g
Nutrition is an estimate calculated from the ingredients listed. Brands vary, so check labels if you track closely.
Frequently Asked Questions
How do I know when the lemon filling is done baking?
I pull mine when the center still jiggles slightly, like a gentle wobble when you tap the side of the pan. The edges should look set but the middle shouldn't be firm yet. It continues to set as it cools, so if you wait until the center looks solid in the oven, you'll overbake it and the texture goes rubbery. I've learned this the hard way.
Does allulose work in this recipe?
I've tested these with both allulose and erythritol. Allulose gives a smoother mouthfeel and doesn't have that cooling aftertaste some people notice with erythritol. It also browns a little more in the oven, so your crust may come out slightly darker. Both work well for keto baking, but if texture is your priority, I'd go with allulose.
What can I use instead of almond flour?
I've made the crust with sunflower seed flour for a nut-free keto version, and it works. The texture is a little different, more dense and less crumbly, but the bars still hold together and taste great. A seed flour blend is another option. I'd avoid coconut flour here because it absorbs too much moisture and the crust comes out dry.
Can I make these dairy-free?
I've swapped the butter for coconut oil and the bars turned out well. The crust has a slightly different flavor, a little more coconut-forward, but the lemon filling masks most of it. A dairy-free butter alternative works too if you want to keep the buttery taste closer to my original version.
Can I skip the arrowroot powder?
You can, but the filling will be thinner and take longer to set. I've tested it without and the bars still work, they just don't slice as cleanly. My swap is about a teaspoon of xanthan gum, which thickens the curd the same way. Between the two, I reach for arrowroot because I like how it sets, but xanthan gum is the easier pantry find for most people.
Signed up to bring dessert to book club Thursday & these are what I’m bringing. Going with the smaller amount of lemon juice since a couple of the ladies are not big on tart. Thanks!
Potluck is the real test. The gloss on the lemon curd fools people, they’re expecting chalky and dense and instead they get that smooth, bright filling.
That slight give in the crust, somewhere between shortbread and something airier, is what every other almond flour bar I’ve made is missing. I really do think it’s the coconut – the texture was nothing like I expected. Plain almond flour crusts just compact into this flat mealy thing where the filling kind of sits on top. This one actually has a crust worth eating.
Press the crust up the sides about a quarter inch before it bakes. Found this on batch five and the bars lift out and cut cleanly in a way they just didn’t before. The filling anchors instead of pulling away from the base, and you get the right ratio of crust to curd in every square. Batch nine in, and it runs on autopilot.
Nine batches in is where it clicks. I landed on that same quarter inch in testing and somehow it didn’t make the instructions. The bars lift so differently once the filling has that edge to hold onto.
Something I didn’t catch until batch four or five: the lemon zest in the crust is doing real work. Once I noticed, it all clicked. The crust is just as tart as the filling, so together they actually taste bright. Four stars because I skipped the full chill time once and watched the filling slowly lose the battle with gravity. The cooling window is real.
The curd doesn’t stop working when it comes out of the oven. It needs that chill to finish setting. Two hours minimum, overnight gets you cleaner cuts.
I’ve made enough keto lemon bar attempts to be genuinely skeptical of another one, but the coconut flakes in the crust caught my attention. They give it actual structure instead of that crumbly, greasy almond flour base I’ve come to expect. The filling held its set after a night in the fridge, which no other version I’ve tried has managed.
Browned the butter instead of just melting it and the almond flour crust got this deep, nutty richness that makes the tart filling feel more intentional by contrast. Four stars because I’d push the sweetener in the filling up slightly for my taste, but that crust alone is worth the tweak. If you try it, watch the butter around the 3-minute mark, it turns on you fast.
Haven’t done browned butter here yet. That nutty depth against the lemon filling sounds worth the extra step. Three minutes is exactly when mine goes dark.
I want to make these in a muffin tin instead of the square pan (bringing them to a work thing next week and individual portions just make more sense than trying to slice and serve) but I’m not sure if the almond flour crust is going to hold its shape when you pop them out or just crumble everywhere. Does the bake time change much too, or is that 10-12 minute window still roughly what I’m aiming for?
Muffin tin should work. Press the crust really firmly up the sides and let them cool all the way before removing (that’s where almond flour gets you if you rush it). Bake time drops a bit, check the crust at 8 minutes, filling around 10.
Making these next weekend and wondering if I can assemble Saturday night. Will the shortbread get soggy sitting under the lemon filling overnight, or is same-day the only way?
The crust holds up overnight, especially in the fridge. Slice them cold and the cuts are actually cleaner than same-day. The almond flour base doesn’t go soggy the way regular shortbread does.
made these yesterday and the arrowroot powder really thickens the filling. does the crust recipe work without coconut flakes? i have some but wondering if i can skip them next time
You can skip them but the crust will be softer, more like a sandy shortbread. The coconut adds texture and helps it hold together. Still works without though.
I absolutely loved this! The buttery crust pared with the tart lemon curd was so delicious. I added a tiny bit more lemon zest and minced up some basil and added that too. I know it sounds odd, but it gave the bars a brighter flavor. I might try a hint of orange zest next time.
Basil in lemon bars. I’ve never tried that but now I’m curious how the herb flavor worked with the sweetness. Orange zest would be good too, I do orange in the crust sometimes.
