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’m not a fan of icing. Can I make this in a loaf pan? Hav you tried this? Any suggestions for oven temp and bake time?
Thanks
No, I have not tried it. I think you will need to experiment but most loaf cakes take at least 45 to 50 minutes to bake through.
I have used this recipe for many birthday cakes with so much success! Thank you for this delicious and healthy recipe.
Made this for my birthday. Had a social distancing party with neighbors and they all were asking what the heck made this cake Keto cause it was so good. Easy to make. Great flavor. Thank for making my birthday gathering a hit with this recipe.
So great to hear!
This cake Is not delicious . I really can’t serve it. The texture was gritty from the almond and coconut flours I guess. It didn’t rise very much but that wasn’t the problem. Sorry can’t say it was wonderful. Guess it was for everyone one else.
Please tell me what brands of almond and coconut flour you used. Because the cake, made properly, is not at all gritty, and it rises quite nicely.
Recipe says “1 medium zucchini (@200g)“. 200g is a little less than 1 cup. My medium zucchini shredded yielded 2 cups shredded. Do I use 2 cups shredded or 1 cup?
Cups are not a great measurement for something like grated zucchini, since packing it can make a huge difference to the weight in the cup. So your equivalency of “200g is a little less than a cup” is not at all accurate here. That equivalency is more for items like flour and sugar.
But if you got 2 cups and you didn’t pack it hard into the cup, then go with that. Once it’s squeezed and drained, then it becomes more like a cup, hard-packed.
Made this for my husband’s birthday. We LOVED it. Some keto baking is bland, but not this one, tons of lemon flavour and moist but light cake. Another win!
So glad to hear it!
This cake was so delicious and the lemon frosting add a great touch to the overall flavor. Love that I have another option for all of the zucchini growing in my garden.
This cake is a perfect summer dessert! I love the blueberry and zucchini combo!
This is so good! Very flavorful and moist!!
I only had one pan, and I was too lazy to bake 2 layers separately, so I risked it and made one. I was hoping to cut it, but quickly realized that wouldn’t work, so I poked holes all around it and poured all the frosting on top. For some reason the frosting turned out very liquid ( I guess I softened the butter and cream cheese too much), so everything sort of went wrong 😀 And nonetheless, it turned out absolutely delicious. I think it’s one of my favorite recipes so far, and I tried – and loved! – at least a couple of dozen of yours. Next time I will try making the same amount of ingredients, but bake it in a smaller pan. If the cake is higher, I think it might be possible to cut it in two. Just wanted to share my experience.
Thanks a lot for another great recipe!
What’s the sugar content in this recipe?
I don’t calculate that because I think it’s irrelevant (carbs are the important piece here and since sugars are carbs, it’s not going to be more than the carb count) but you are welcome to calculate it yourself using any number of online resources.
Can you use collagen peptides in place of whey protein powder?
Nope! Don’t do it! The only good replacement is egg white protein. collagen makes baked goods gummy.
I made this today and it smells absolutely delishes! I followed the recipe to the T but for some reason the batter did not rise. Not sure where I went wrong. Cant wait to cut into it
I wonder if your baking powder is old? Keto cakes don’t rise as much as conventional ones but they should rise some.
I plan on making this Tueaday, but I couldn’t find unflavored protein powder, so I got smooth vanilla… do you think it will make a big difference? Thanks.
Often those protein powder flavours can be a bit strong. You may get more vanilla flavour so add a touch more lemon if you can to offset it.
That looks delicious. I’m wondering. Can I substitute the wey protein powder for batted egg whites? If so, how many? TIA
No, only egg white protein powder can replace the whey.
I don’t have whey protein but i do have pea protein powder. Organic protein powder. Is that ok to use instead?
I hope so but some pea protein is greenish in colour…