These easy Keto lemon bars are a crowd-pleaser. They are super moist and just on the right side of zingy. Only 5 minutes prep and ready in just 40 minutes.
This recipe is a Sugar Free Londoner classic. It has been on the blog since 2019 and consistently gets 5-star reviews. "Delicious, light and fluffy," wrote a reader recently. She had just made it for the second time. "They come out perfect every time."
These keto lemon bars are definitely not traditional. In fact, when I first created this recipe, I was not aware that classic lemon bars have a shortbread crust and a lemon curd filling!
My recipe is essentially a keto lemon cake sliced into bars. Due to the addition of sour cream, it has a super moist crumb. I find there is a hint of baked cheesecake texture.
Classic or not, this is a truly delicious dessert experience. I am giving you plenty of topping options further down, including a sugar free lemon curd frosting.
Here are the ingredients you'll need for easy sugar free lemon bars:
- Eggs - large. These must be at room temperature to help the cake rise better.
- Butter - Should be very soft. I warm mine in the microwave until it is almost melted.
- Sour Cream - room temperature. You could also use cream cheese.
- Lemon - We need both the juice and the zest. Make sure you buy unwaxed lemons. For me, 1 ½ lemons yielded ¼ cup lemon juice. For extra zing, you could increase the amount of lemon juice by up to 2 additional tablespoons.
- Almond flour - I've used ground almonds for this cake, which is equivalent to coarse/grainy almond flour. This helps with creating that super juicy sponge cake. Reduce the amount by ¼ cup (25g) for super fine almond flour.
- Baking powder - Check that it is fresh.
- Powdered sweetener - I used erythritol. However, this recipe will work just as well with Swerve, monk fruit sweetener blends, Bocha Sweet or allulose. Check that you are using a 1:1 sugar substitute.
See the recipe card for full information on ingredients and quantities.
Let's make keto lemon bars! Here are step-by-step images. For more details, scroll down to the recipe card.
Beat the eggs until frothy. Then add the softened butter and the sour cream and blend in a food processor or with an electric mixer until combined.
Add the lemon juice, lemon zest and powdered sweetener and blend.
Last, add the remaining dry ingredients - almond flour and baking powder. Mix until smooth. Let the batter sit for a couple of minutes to thicken. It should be thick but pourable.
Line a small casserole dish or cake pan with parchment paper. I used a 9 x 6-inch dish, but it could even be slightly bigger - my cake bar slices were a generous 4 cm / 1.5 inch tall. Fill in the batter and smooth the top with a spatula.
Bake the cake on the middle oven shelf for 35-40 minutes or until a toothpick inserted comes out clean.
#1 Use the lemon zest! It really lifts the flavor. It's my secret ingredient.
#2 Taste the batter and adjust the sweetener if required. I don't like my cakes too sweet. You may prefer a little more sweetness. There is no right or wrong here!
I decided to keep it quick and simple and dusted powdered sweetener over the cake.
Here are more topping ideas:
Sugar Free Lemon Drizzle:
Mix 4 tablespoons lemon juice with 4 tablespoons powdered sweetener and drizzle over the cake.
Low Carb Lemon Glaze:
Stir together 4 tablespoons each of melted butter, cream, powdered sweetener and the juice of 1 lemon. Wait until the mixture starts to cool and thicken, then pour over the cake.
Simple Keto Lemon Cream Cheese Frosting:
Mix ½ cup cream cheese, 4 tablespoons of powdered sweetener, a squeeze of lemon juice and grated lemon zest. Spread over the lemon bars and grate extra lemon zest on top.
Pull-out-all-the-stops Keto Lemon Curd Frosting:
Make a batch of sugar free lemon curd and cool in the fridge. Whip 1 cup / 240ml of heavy cream until stiff and fold in the cold lemon curd. Spread over the cooled cake and grate lemon zest on top.
Coconut flour: I know some of you cannot have almond flour. You can try making this recipe using 1 cup of coconut flour in place of the almond flour plus an additional egg. A reader has tested this variation and reported that it works well.
Dairy-free: For dairy-free keto lemon bars, use coconut yoghurt or coconut cream in place of the sour cream. Also, use coconut oil or a dairy-free butter substitute.
Less fat: Use Greek yoghurt in place of sour cream.
Yes! This recipe also works well in a loaf pan. The baking time will increase to around 45-50 minutes.
Yes, you can add ⅓ cup of fresh blueberries into the cake batter. This way, it will taste similar to my keto blueberry bread.
Yes. Fill the batter into muffin liners and bake for 25 minutes. To make cupcakes, add the cream cheese or the lemon curd frosting described above.
Store keto lemon bars in an airtight container at room temperature for up to 2 days or in the fridge for up to 5 days.
All almond flour cakes freeze well. I pre-slice this cake into bars and freeze them for up to 3 months. This way, I can defrost one slice at a time overnight.
More Keto Lemon Desserts
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Keto Lemon Barsfrom Sugar Free Londoner
Note: The servings slider only changes the first amount in each line and not any subsequent amounts. Please make your own calculations where necessary.
- 4 eggs large, room temperature
- ½ cup / 120g sour cream room temperature
- ½ cup / 120g butter must be very soft
- ¼ cup / 4 tbsp lemon juice I used 1 ½ lemons
- zest of 1 lemon
- 2 cup / 200g almond flour Use 2 tablespoons less for super-fine almond flour
- 2 teaspoon baking powder
- ⅓ cup / 40g powdered erythritol or more, to taste.
- Preheat the oven to 175 Celsius / 350 Fahrenheit.
- Beat the eggs until frothy. Add the sour cream and softened butter and blend with a food processor or electric mixer until combined.
- Add lemon juice, the grated zest of 1 lemon and ⅓ cup powdered erythritol or powdered sugar substitute of your choice. Blend.
- Lastly, add the almond flour and baking powder and mix until you have a smooth batter. Adjust sweetener to taste, adding more if required.
- Line a 9x6 inch pan with parchment paper and fill in the batter.
- Bake in the middles shelf of the oven for 35-40 minutes until the top is lightly browned and a skewer inserted comes out clean.
- Leave to cool completely before cutting or removing from the pan. Almond flour cakes are fragile when hot, but they firm up as they cool down.