Blueberries are my go-to when I’m low carbing it, and this layered cake is one for the books! It’s moist, delish, loaded with blueberries, and most importantly, it’s low carb so you can indulge guilt-free!
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I reach for this Low-Carb Blueberry Lemon Cake when I want something that feels a little special. The flavors are clean and simple, the texture is soft without being dense, and it slices beautifully. It’s the kind of cake you can serve after dinner and not regret, or keep in the fridge for a few days and grab when the sweet craving hits.
If you’ve ever wanted a dessert that feels fresh instead of heavy, and indulgent without going overboard, this one earns a spot in your rotation. It’s easy, dependable, and exactly the kind of low-carb treat I actually look forward to eating.
Ingredients
Sponge Cake
- Egg whites – Save the yolks for another recipe.
- Cream of tartar – You can buy this in your grocery store, wherever spices are sold.
- Egg yolks – Use large eggs so the sponge stays balanced and rich.
- Lakanto Golden sugar substitute – I like Lakanto Golden here because it sweetens without the gritty texture some substitutes leave behind.
- Lemon juice – Fresh lemon juice gives the brightest flavor; bottled juice can taste flat.
- Lemon zest
- Almond flour – Use finely ground almond flour; coarse almond meal can make the sponge dense.
Blueberry Frosting
- Mascarpone – Mascarpone should be cool but soft; if it’s too warm, the frosting can turn loose. You can use softened cream cheese if you can’t find mascarpone.
- Erythritol powder – Powdered erythritol blends smoothly and helps keep the frosting from feeling grainy.
- Stevia powder – Or your favorite sweetener.
- Heavy whipping cream – You need whipping cream to whip up nicely for the frosting.
- Blueberries – Fresh or frozen, both work; if frozen, thaw and drain well to avoid thinning the
Blueberry Jelly
- Blueberries
- Water
- Stevia powder – Or your favorite sweetener.
- Lemon juice
- Gelatin powder – Knox is the most common brand, and you can find it wherever Jell-O is sold.
How to Make Blueberry Lemon Cake
Scroll down for the full recipe card with exact measurements and printable instructions.
Preheat the oven to 350°F (180°C). Line a 9-inch springform pan with parchment on the bottom and sides so the sponge releases cleanly after baking.
Add the egg whites and cream of tartar to a stand mixer fitted with the whisk attachment. Whip until medium-stiff peaks form. Stop as soon as the whites hold their shape so the meringue stays stable.
In a separate bowl, beat the egg yolks and Lakanto sugar substitute with a hand mixer for 2 to 3 minutes until pale and creamy. Add the lemon juice and lemon zest and mix again.
Add the almond flour to the yolk mixture and mix until combined. The batter will be thick at this stage.
Use a silicone spatula to gently fold one-quarter of the whipped egg whites into the batter, loosening it. Fold in the remaining whites in two additions, gently lifting and turning the batter to keep as much air as possible.
Pour the batter into the prepared pan and smooth the top. Tap the pan lightly on the counter to release any large air bubbles.
Bake for about 35 to 40 minutes, until the sponge is set and lightly golden. Let the cake cool completely before removing it from the pan. Once cooled, slice the sponge horizontally into three even layers using a long serrated knife.
In a large mixing bowl, combine the mascarpone, powdered erythritol, and stevia. Beat until smooth. Slowly add the heavy cream and beat for about 3 minutes until thick and fluffy.
Add the blueberries and beat on high speed until the frosting turns a soft purple color and the berries are fully blended. Refrigerate the frosting for at least 2 hours so it firms up for layering.
Add all the jelly ingredients to a small saucepan and simmer for about 5 minutes, stirring occasionally. Remove from heat and blend briefly using a small blender or immersion blender until smooth.
Transfer the jelly to a bowl and refrigerate for at least 2 hours, or until fully set but still spoonable.
Place the first sponge layer on a cake stand. Spread an even layer of blueberry frosting on top.
Transfer some frosting to a piping bag fitted with a round tip and pipe a border around the edge of the cake layer. Spoon half of the blueberry jelly inside the border, keeping it contained.
Place the second sponge layer on top and repeat the frosting and jelly steps. Finish with the final sponge layer and frost the outside of the cake with the remaining blueberry frosting.
Decorate with fresh blueberries or lemon zest if desired. Keep the cake refrigerated until ready to serve.
Chef Jenn’s Tips
- A springform pan makes removing the sponge much easier without tearing the layers.
- Chill both the frosting and jelly fully before assembling so the layers stay clean and defined.
- Use a piping bag to create a frosting “dam” so the jelly doesn’t leak out between layers.
- Keep the cake refrigerated until serving since the mascarpone frosting softens quickly at room temperature.
Serving Suggestions
Serve this Low-Carb Blueberry Lemon Cake well chilled for clean slices and the best texture. It pairs beautifully with coffee, hot tea, or a light after-dinner espresso. I love serving this cake after a hearty meal of Baked Pesto Salmon and Green Beans Amandine with Bacon, or a yummy Cheeseburger Casserole.
Storage
Store the keto-friendly cake covered in the refrigerator for up to 3 days. Keep chilled until serving, as the frosting softens quickly at room temperature.
Add Preferred SourceLow-Carb Blueberry Lemon Cake
Ingredients
Sponge Cake
- 5 egg whites
- ¼ teaspoon cream of tartar
- 5 egg yolks
- ¼ cup Lakanto Golden sugar substitute
- 2 tablespoons lemon juice
- lemon zest
- 1¼ cups almond flour
Blueberry Frosting
- 1⅓ cups mascarpone
- 8 tablespoons erythritol powder
- ½ teaspoon stevia powder
- ½ cup heavy whipping cream
- ¾ cup blueberries
Blueberry Jelly
- 1 cup blueberries
- ½ cup water
- ½ teaspoon stevia powder
- 1 teaspoon lemon juice
- 2 tablespoons gelatin powder
Instructions
- Preheat the oven to 350°F (180°C). Line a 9-inch springform pan with parchment on the bottom and sides.
- Add the egg whites and cream of tartar to a stand mixer. Whip on high until medium-stiff peaks form, stopping before the whites become dry.
- In a separate bowl, beat the egg yolks and Lakanto for 2 to 3 minutes until pale and creamy. Add the lemon juice and zest and mix well, then stir in the almond flour.
- Add one-quarter of the whipped egg whites to the batter and mix gently with a spatula to loosen it. Fold in the remaining egg whites in two additions, keeping the batter light and airy.
- Pour the batter into the prepared pan, spread evenly, and tap the pan lightly to release air bubbles. Bake for about 35 minutes, until set. Cool completely in the pan, then remove and slice the cake horizontally into three even layers.
- To make the frosting, mix the mascarpone, erythritol, and stevia until smooth. Slowly add the heavy cream and beat on medium-high for about 3 minutes until thickened. Add the blueberries and mix on high speed until the frosting turns purple. Refrigerate for at least 2 hours then transfer to a piping bag fit with a large round hole.
- To make the jelly, combine all jelly ingredients in a small saucepan and simmer for about 5 minutes. Blend briefly with an immersion blender until smooth, then refrigerate for at least 2 hours to set.
- To assemble, place one sponge layer on a cake stand and frost the top. Pipe a frosting border around the edge and fill with half of the blueberry jelly. Add the second layer and repeat, then top with the final layer and frost the entire cake. Decorate as desired and keep refrigerated until serving.
Notes
Chef Jenn’s Tips
- A springform pan makes removing the sponge much easier without tearing the layers.
- Chill both the frosting and jelly fully before assembling so the layers stay clean and defined.
- Use a piping bag to create a frosting “dam” so the jelly doesn’t leak out between layers.
- Keep the cake refrigerated until serving since the mascarpone frosting softens quickly at room temperature.
Nutrition
A Note on Nutritional Information
Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed. Erythritol carbs (sugar substitutes) are not included in the carbohydrate counts as they have been shown not to impact blood sugar, and they have zero calories and zero carbs. Net carbs are the total carbs minus fiber.
