Showcase the best of summer’s bounty with this beautiful Keto Lemon Blueberry Layer Cake. Tender and sweet, and bursting with flavor, it has a delectable sugar-free cream cheese frosting. And only 4.8g net carbs per slice!
Need more ideas for your summer zucchini? Check out this list of Keto Zucchini Recipes
Lemon and Blueberry: Classic Summer Flavors
This recipe has long been one of my summer favorites because it brings together so many fresh flavors. I tend to favor keto chocolate cake, but the light tangy sweetness of this Keto Lemon Blueberry Cake wins me over every time. And the zucchini adds wonderful moisture and nutrition.
I know that it can be hard to think about turning on the oven in the middle of summer. I get that, I really do, and I have many wonderful easy keto dessert recipes for those of you who just can’t bear the thought.
But if you’re a bakeaholic like me, sometimes you’ve just got to suck it up and bear it. Because you can’t bake gorgeous keto cakes like this one without a little heat. And sometimes nothing will do but a big layer cake with plenty of creamy frosting. So throw open those windows, blast the fans, or jack up the AC, kids. It’s going to get a little hot in here!
★★★★★
Nancy says: “I have made this cake several times and everyone always wants the recipe! It’s so delicious and moist and the lemon and blueberry flavors are such a wonderful taste of spring. Thanks, Carolyn!“
Ingredients and Substitutions
- Zucchini: This adds wonderful moisture and texture to the cake, along with a boost of nutrition.
- Almond flour: I really feel this cake works best with a finely ground almond flour. If you wish to use coconut flour, follow the basic amounts and instructions for my Keto Chantilly Cake.
- Protein powder: As with many baked goods, this helps the cake rise better and hold its shape. You can use whey or egg white protein powder. Plant-based may work as well but I don’t recommend collagen protein.
- Sweetener: I suggest using a granular erythritol-based sweetener in the cake and a powdered sweetener in the frosting. Please see the Sweetener Options for a more detailed discussion.
- Lemon: This cake recipes uses the zest and the juice. You can also bump up the lemon flavor with a little lemon extract.
- Blueberries: Fresh blueberries work best as they don’t bleed into the batter.
- Cream cheese: This is the base for the super creamy frosting!
- Heavy cream: A little heavy cream helps thin the frosting to a spreadable consistency.
- Baking staples: Butter, eggs, baking powder, vanilla, salt.
How to Make Keto Blueberry Lemon Cake
- Drain the zucchini: Salt and drain the zucchini in a sieve, then squeeze out as much moisture as possible.
- Prepare the batter: Whisk the dry ingredients together. Beat the butter with the sweetener until well combined, then beat in the eggs and extracts. Beat in the dry ingredients and lemon juice. Fold in the blueberries.
- Bake the layers: Spread the mixture evenly in two 8-inch round cake pans. Bake until golden brown and firm to the touch.
- Prepare the frosting: Beat the cream cheese and butter together until smooth, then beat in the sweetener, lemon zest, lemon juice, and cream.
- Frost the cake: Spread the top of the first layer with frosting, then add the second cake layer. Spread the remaining frosting over the top and sides.
- Garnish: Decorate with additional blueberries and lemon zest.
Carolyn’s Tips for Success
Squeeze the zucchini very dry so the cake isn’t mushy. You can do this with your hands, squeezing it in your palm and pressing it out in the sieve, or you can wrap it a tea towel and twist it.
Make sure the butter is properly softened! I find I sometimes have to give it a quick 10-second zap in the microwave, because room temperature is not always soft enough. It will beat more smoothly if it’s properly softened (but not melted), and become fluffier when you add the sweetener.
Don’t skip the grated lemon zest in either the cake or the frosting, as it gives the best flavor. You can also add some lemon extract to the cake, if you want more lemon flavor.
The frosting makes enough for the top of each layer and a thin “crumb coat” on the sides. If you want a fully frosted cake, I recommend increasing the frosting by about 30%. This will change the nutritional content.
Sweetener Options
For the cake layers, an erythritol sweetener that doesn’t contain any allulose will work best. Good brands to consider include Impact Sweetener or Lakanto. Sweeteners with any amount of allulose will cause the cake to brown too quickly and it may even taste burnt.
If you wish to cut down on erythritol, try using 1/4 cup and supplementing the sweetness with a highly concentrated sweetener such as pure stevia or monk fruit.
The frosting requires a powdered sweetener to have the right volume and structure. But both erythritol and allulose based sweeteners work.
More Delicious Keto Blueberry Recipes
Keto Lemon Blueberry Zucchini Cake
Equipment
Ingredients
Cake:
- 1 medium (196 g) zucchini, shredded, (about 200g)
- 1/4 tsp salt
- 2 1/2 cups (280 g) almond flour
- 1/2 cup (54 g) unflavoured whey protein powder
- 1 tbsp baking powder
- 1/4 tsp salt
- 1/3 cup (75.67 g) butter, softened
- 1/2 cup (95 g) granular sweetener, erythritol recommended
- 3 large eggs, room temperature
- 1 tbsp lemon zest
- 1/2 tsp vanilla extract
- 1/2 tsp lemon extract, (optional)
- 3 tbsp (45.65 g) freshly squeezed lemon juice
- 1 cup (148 g) blueberries, fresh works best
Lemon Frosting:
- 8 ounces (226.8 g) cream cheese, softened
- 1/2 cup (113.5 g) butter, softened
- 1/2 cup (95 g) powdered sweetener
- 2 tbsp freshly grated lemon zest
- 2 tbsp (30.43 g) freshly squeezed lemon juice
- 2 tbsp (30.43 g) heavy whipping cream
Garnish:
- fresh blueberries
- lemon zest
Instructions
Cake
- Place the zucchini in a sieve and sprinkle with the salt. Toss to combine. Let drain 1 hour and then squeeze out the zucchini to release as much moisture as possible.
- Preheat the oven to 325ºF and grease 2 (two) 8-inch round cake pans very well. Line the bottoms with parchment paper and grease the parchment.
- In a medium bowl, combine the almond flour, protein powder, baking powder and salt.
- In a large bowl, beat the butter with sweetener until well combined. Beat in the eggs one at a time, scraping down the sides of the bowl and the beaters as needed. Then beat in the zucchini, lemon zest, and vanilla extract.
- Beat in the almond flour mixture until well combined, then beat in the lemon juice. If your batter is quite thick, add a little water, 1 tbsp at a time, until a spreadable consistency is achieved.
- Gently fold in the blueberries. Divide the batter between prepared pans and spread evenly to the edges. Bake 30 to 40 minutes, until golden brown around the edges and the top is set to the touch.
- Remove and let cool completely in the pans, then run a sharp knife around the edges to loosen.
Frosting
- In a large bowl, beat the cream cheese and butter together until smooth. Beat in the sweetener until well combined, then beat in the lemon zest.
- Beat in the lemon juice and cream until well combined.
To Assemble
- Place one cake layer on a serving platter and spread the top with about 1/3 of the frosting. Add the second cake layer and spread the remaining frosting over the top and the sides.
- Garnish with additional fresh blueberries and lemon zest.
Nutrition
Are blueberries keto-friendly?
The reality is that any food can be “keto” if you eat small enough amounts of it. But blueberries, while super healthy and full of antioxidants, are not the most keto friendly fruit. 1 cup of raspberries has 15g of carbs and 8g of fiber, but blueberries weigh in at 21g of carbs and only 3.6g of fiber.
Again, it’s not that blueberries are bad for keto diets, but they do have more carbs than you’d think so it’s wise to be conscious of how many you consume. One of the main ways I reduced the carbs in this cake was by cutting back a bit on the blueberries. But don’t worry, you still get plenty of delicious ripe blueberries in every bite. I also cut back on the almond flour and added more protein for a lighter, fluffier cake!
Nutritional Disclaimer
Please note that I am not a medical or nutritional professional. I am simply recounting and sharing my own experiences on this blog. Nothing I express here should be taken as medical advice and you should consult with your doctor before starting any diet or exercise program. I provide nutritional information for my recipes simply as a courtesy to my readers. It is calculated using MacGourmet software and I remove erythritol from the final carb count and net carb count, as it does not affect my own blood glucose levels. I do my best to be as accurate as possible but you should independently calculate nutritional information on your own before relying on them. I expressly disclaim any and all liability of any kind with respect to any act or omission wholly or in part in reliance on anything contained in this website.
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I’ve never used whey protein; exactly what purpose does it serve in this recipe? Can it be omitted or substituted? (I think I’ve only seen it come in ginormous containers? I’m not sure I’d ever use it again…). Great job on recipes – I’m trying to omit carbs in my life and having a hard time sticking to it without a variety of some tasty treats and flavorful recipes – can’t wait to try some of these!
For some reason the comments didn’t load before I asked the question – so I see my answer!
Gluten is a protein and in its absence a dry protein like egg white powder or whey protein helps the baked goods rise and hold their shape. And you can get smaller containers and bags of it!
Thanks, I wondered too?
Thank You.
The cake is wonderful.
The zucchini gives it a wonderful texture.
I did notice that the recipe has no starch and a person just has to have starch when cooking with coconut flour and almond flour. Which is a problem if going low carb.
So,— I see; you are telling me that the whey powder does the same thing. That is very good information, that I needed.
I seem to be allergic to just more than gluten. I was doing great on a low carb diet and when I added more into my diet – well gluten for sure; and that is all I can figure. I do hate psoriasis in my ears, even worse than in the joints of my toes and fingers.
Can the whey prktein be substituted with other plant based protein powder?
Yes, those should work. the only one that really doesn’t work, in my experience, it collagen protein.
I love both lemon and blueberry! I have a recipe for brownies with zucchini that I love so I can’t wait to try these!
I dont have two pans, can i bake the cake in one pan and cut it after? Or i need to bake it two times?. Thank you, love all your recipies. Greetings from Spain
I would bake the first layer and then remove it after it cools for a bit, and then I would bake the second layer.
Made the cake today. Absolutely delicious. Super fresh and tasty. Love it. Thank you
Now THAT looks like one yummy cake!!!
I’ve never tried baking with or using whey powder – does it help to bind it all together? Can I substitute with something else?
Will definitely try this – thanks!
{And it looks so pretty too 😉 }
Heidi xx
Ok, just saw someone else also asked they question about the whey…
xx
It helps baked goods rise and hold their shape in the absence of gluten (another dry protein). But you can use powdered egg whites instead.
I’m definitely making this cake! Thanks so much! Yum!
Pinned! I can’t wait to try this cake!!
About how many zucchini for 3 cups shredded?
Ilove your recipes! My question is can I substitute vanilla protein powder for unflavored?
Yes, but it will give a distinctive vanilla flavour so leave out any additional vanilla.
Hi Carolyn, can you make this with coconut flour instead of almond flour? I don’t happen to like almond flour or almond meal…thank you!
Wendell did you try it with coconut flour?
I like to save my coconut flour for keto bread.
I think the coconut flour would suck up all the moisture. So maybe you would not even need to drain/squeeze the zucchini
?
You have listed Swerve Sweetener and then Swerve – 1/2 cup each – isn’t this the same thing?
Why not list Swerve once as 1 cup?
Read the recipe a little more closely…I list an option for 1/2 tsp liquid stevia, which I used, OR another 1/2 cup Swerve. So it’s what YOU prefer.
Duh – see that now! Thank you!
No worries!
This revised recipe does not mention stevia at all. I would like to use some liquid stevia so please advise how much and where in the current recipe. Thanks!
Has anyone tried different sweeteners other than swerve? I have xylitol, trivia and stevia on hand!
Any of those will work in the cake but you need a powdered sweetener for the frosting.
WOW…another great recipe to use the blueberries from my bushes…thanks again, Carolyn!
Sounds and looks delicious Carolyn, and I have all these ingredients ready to go! Thanks for the recipe.
This looks delicious!! Do you think it would work if I baked this as a loaf?
Oh, wow!!! I wish today were my birthday!! Lemon frosting AND blueberries=brilliant.
Hey I don’t have whey protein at home is it ok not to use or any subs for it
yOu need a dry protein to replace the gluten, otherwise your cake will not rise as well.
Can I use egg white protein powder I can not have whey.
Sure, that should be fine.
Can I use Grass fed Hydrolysis Collogen protein powder or Gelatin perhaps Great Lakes. pure unflavored Kosher Beef Hide Peotein in place of the What protein
No. They tend to make things gummy. You can try egg white protein though.
What do you do with the zuchinni once it’s drained? Mix with the dry ingredients or add into the egg mixture?
Sorry, all fixed. I had “vanilla” listed twice in the instructions and I meant zucchini for one of them.
Wow, this cake. That’s all I can manage to utter. Texture, taste….all perfect.