Keto Lemon Bars

Ingredients & Substitutions

Here I explain the best ingredients for my keto lemon bars recipe, what each one does, and substitution options. For measurements, see the recipe card.

Shortbread Crust:

• Wholesome Yum Blanched Almond Flour – It has a finer grind than other brands, for a better texture in your crust. Many other brands turn out gritty. If you want to use coconut flour for a nut-free version, I recommend using my coconut flour pie crust recipe.
• Besti Monk Fruit Allulose Blend – Other keto sweeteners should also work okay in the crust, but Besti locks in moisture so it turns out less dry. If you want to cut down on the number of different sweeteners you need, powdered Besti (in the filling below) should work fine in the crust as well.
• Coconut Oil – I’ve also had success using unsalted butter or butter flavored coconut oil.
• Egg (just one), Vanilla Extract (I like this brand), and Sea Salt (to balance the sweetness)

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Lemon Filling:

• Besti Powdered Monk Fruit Allulose Blend – The type of sweetener is super important for the right texture in your sugar free lemon bars! Anything granulated or containing erythritol won’t dissolve and can crystallize, leading to a grainy, gritty texture. Most brands labeled “monk fruit” or “stevia” have these issues. Liquid sweetener won’t work either, as the filling won’t set. Powdered Besti is the only one I recommend here for a smooth texture, although powdered allulose would also work — you’ll need an extra 1/3 to 1/2 cup. Also note, some older reviews say these bars aren’t sweet enough, but in June 2025 I increased the amount of sweetener to address these.
• Wholesome Yum Almond Flour & Eggs – To set and thicken the filling. I don’t recommend egg substitutes here.
• Lemons – I highly recommend fresh lemon juice here, plus you’ll need the zest from a few of them, anyway. I use this lemon squeezer, and it makes juicing lemons so fast and easy. I usually just grab a big bag from my local warehouse club! I have made these keto lemon bars using this organic bottled lemon juice as well, but even with this quality brand, the flavor is nowhere near as good as fresh.

How To Make Keto Lemon Bars

I have step-by-step photos here to help you visualize the recipe. For full instructions with amounts and temperatures, see the recipe card.

1. Make the filling. Juice and zest the lemons. In a large mixing bowl or a huge measuring cup (I use this one for convenient pouring later), stir together the almond flour, powdered Besti, and salt. Whisk in the eggs, then the lemon juice and zest. Set aside near your oven area.

2. Make the crust dough. In another large bowl, whisk the almond flour, Besti, and salt for the crust, breaking up any lumps. Mix the vanilla into the melted coconut oil or butter, then add to the dry ingredients. Add the egg and mix until a crumbly dough forms.
3. Bake the crust. Press the dough into a square baking dish (I use this one). Poke holes with a fork to prevent bubbling, then bake until firm and golden on the edges.

4. Bake with filling in a water bath. While the crust is still hot, immediately pour the filling over it. Place into a hot water bath and bake again until almost set, but still a bit jiggly — a lot like a keto cheesecake. I use this baking dish for the water bath, and fill it with boiling water from a kettle before placing the smaller dish of bars inside.
5. Cool gradually, then chill to set. Turn the oven off and prop the door open with a wooden spoon. Cool like this until the filling is set and lukewarm (not hot or cold), then cool completely on the counter. Finally, cover and refrigerate the keto lemon bars to set completely before slicing.