Keto Lemon Cake with Blackberry Mascarpone Frosting 🍋

Spring has a flavor — and it tastes exactly like lemon. Bright, tangy, sweet, and impossibly refreshing, lemon desserts have always felt like the perfect way to celebrate the season. This Keto Lemon Cake with Blackberry Mascarpone Frosting is our Easter dessert showstopper — gorgeous enough to impress every guest at the table, and low carb enough that you can have a second slice without a second thought.

The pastel purple of the blackberry mascarpone frosting makes it naturally Easter-colored without a drop of artificial dye — and at just 5g net carbs per slice, it fits beautifully into your keto lifestyle. Let’s bake! 🐣

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Why You’ll Love This Recipe

• Naturally Easter-colored — the blackberry frosting is a gorgeous pastel purple 💜
• Only 5g net carbs per slice — dessert without the guilt
• No one will know it’s keto — it tastes like a traditional bakery lemon cake
• Make ahead friendly — perfect for stress-free holiday entertaining
• Gluten free and grain free — made entirely with almond and coconut flour

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The Macros

Per slice (based on 12 slices):

	Per Serving
Calories	~320
Net Carbs	~5g
Protein	~8g
Fat	~28g

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Ingredients

🍋 For the Lemon Cake Layers

(Makes two 8-inch round layers)

• 2½ cups superfine blanched almond flour
• ¼ cup coconut flour
• 1½ tsp baking powder
• ¼ tsp baking soda
• ¼ tsp sea salt
• 4 large eggs, room temperature
• ½ cup butter, melted and cooled
• ½ cup granulated erythritol or monk fruit sweetener
• ¼ cup heavy cream
• 3 tbsp fresh lemon juice (approximately 2 lemons)
• 2 tbsp lemon zest (approximately 2 lemons)
• 1 tsp vanilla extract
• 1 tsp lemon extract

💜 For the Blackberry Mascarpone Frosting

• 8 oz mascarpone cheese, softened
• 4 oz cream cheese, softened
• 1 cup heavy whipping cream
• ½ cup powdered erythritol or powdered monk fruit sweetener
• 3 tbsp sugar-free blackberry jam (Smucker’s Sugar Free works great!)
• 1 tsp vanilla extract
• Pinch of sea salt

🍋 Optional Garnish

• Fresh blackberries
• Lemon slices
• Lemon zest

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Instructions

Step 1 — Prep

Preheat your oven to 350°F. Grease two 8-inch round cake pans and line the bottoms with parchment paper rounds. Set aside.

Step 2 — Mix the Dry Ingredients

In a medium bowl whisk together the almond flour, coconut flour, baking powder, baking soda, and salt until well combined. Set aside.

Step 3 — Mix the Wet Ingredients

In a large bowl whisk together the eggs, melted butter, sweetener, heavy cream, lemon juice, lemon zest, vanilla extract, and lemon extract until completely smooth and combined.

Step 4 — Combine

Gently fold the dry ingredients into the wet ingredients until just combined — be careful not to over-mix! Allow the batter to rest for 2 minutes so the coconut flour can fully absorb the liquid.

Step 5 — Bake

Divide the batter evenly between the prepared cake pans. Bake for 22–25 minutes, or until a toothpick inserted in the center comes out clean and the tops are lightly golden. Allow the cakes to cool in the pans for at least 30 minutes before transferring to a wire rack to cool completely. Do not rush this step — the layers need to be completely cool before frosting! ⏱️

Step 6 — Make the Frosting

In a large bowl using a hand mixer, beat the mascarpone and cream cheese together until smooth and fluffy — about 2 minutes. Add the heavy whipping cream, powdered sweetener, vanilla extract, and sea salt, and beat until thick and creamy. Add the sugar-free blackberry jam and beat just until fully incorporated and the frosting turns a beautiful pastel purple. Taste and adjust sweetness as needed. Refrigerate until ready to use.

Step 7 — Assemble

Place the first cake layer on your serving plate or cake stand. Spread a generous layer of blackberry mascarpone frosting evenly across the top. Add the second cake layer and frost the top and sides of the cake. Garnish with fresh blackberries, lemon slices, and a sprinkle of lemon zest for a stunning Easter presentation. 💜🍋

Step 8 — Chill & Serve

Refrigerate the assembled cake for at least 1 hour before slicing and serving — this helps the frosting set and makes for clean, beautiful slices!

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Substitution Tips

Sweetener — Any granulated keto sweetener works in the cake batter — erythritol, monk fruit, or allulose all work well. For the frosting, make sure to use a powdered sweetener to avoid a gritty texture. You can make your own by blending granulated erythritol in a blender until fine.

Almond Flour — Always use superfine blanched almond flour for the best texture. Regular almond meal is too coarse and will result in a crumbly, dense cake. Do not substitute coconut flour 1:1 for almond flour — they behave very differently in baking!

Blackberry Jam — No sugar-free blackberry jam? Any sugar-free berry jam works beautifully — raspberry, strawberry, or mixed berry all give gorgeous color and flavor. You can also fold in a small handful of fresh blackberries instead.

Mascarpone — If you can’t find mascarpone, full-fat cream cheese works as a substitute though the frosting will be slightly tangier and less silky in texture.

Butter — Swap for melted coconut oil if you prefer a dairy-free cake layer. Use refined coconut oil to avoid any coconut flavor coming through.

Lemon Extract — If you don’t have lemon extract, simply add an extra tablespoon of fresh lemon juice and an extra teaspoon of lemon zest for a more pronounced lemon flavor.

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Make Ahead & Storage Tips

Make Ahead: This cake is perfect for making ahead — in fact it tastes even better the next day as the flavors develop! Bake the cake layers up to 2 days in advance, wrap tightly in plastic wrap, and store at room temperature. Make the frosting fresh and assemble the day before serving. Refrigerate overnight and bring to room temperature for 20–30 minutes before slicing.

Storage: Store the frosted cake covered in the refrigerator for up to 4 days. Cover any cut sides with plastic wrap to prevent the cake from drying out.

Freezing: The unfrosted cake layers freeze beautifully for up to 3 months. Wrap each layer tightly in plastic wrap and place in a freezer bag. Thaw at room temperature before frosting and assembling.

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Pro Tips for the Perfect Keto Lemon Cake

🍋 Use fresh lemons — bottled lemon juice simply doesn’t have the same bright, vibrant flavor. Fresh is always best for baking!

🍋 Room temperature ingredients matter — cold eggs and butter straight from the fridge can cause the batter to seize. Let everything come to room temperature first!

🍋 Don’t over-mix — mix until just combined to keep the cake tender and light

🍋 Zest before you juice — always zest your lemons before cutting and juicing them — it’s much easier!

🍋 Cool completely — we know it’s tempting but rushing the cooling process will cause the frosting to melt right off the cake!

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Cross-Link: Part of Our Keto Easter Dessert Series! 🐣

This Keto Lemon Cake is part of our complete Keto Easter Dinner Guide — check it out for a full menu of keto-friendly Easter dinner ideas from glazed ham to bacon wrapped asparagus! 🔗

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Have you made this cake? Drop a photo and your review in the comments below — I absolutely love seeing your creations! 🍋👇

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⚠️ Disclaimer: Macro counts are approximate and may vary based on specific brands and portion sizes used.