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Keto Poppy Seed Lemon Cake with Blackberry Buttercream

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This keto poppy seed lemon cake is soft, buttery, and full of fresh lemon flavor. It’s made with almond flour, coconut flour, and keto-friendly sweetener, making it a perfect low-carb and gluten-free dessert. The creamy blackberry buttercream adds a fruity, slightly tart balance, making each bite irresistible. Perfect for birthdays, tea time, or a special treat!

Ingredients

Scale

For the Cake:

  • 2 ½ cups almond flour
  • ¼ cup coconut flour
  • 2 tsp baking powder
  • ½ tsp baking soda
  • ¼ tsp salt
  • 3 tbsp poppy seeds
  • 4 large eggs (room temperature)
  • ¾ cup granulated erythritol or monk fruit sweetener
  • ½ cup unsalted butter, melted
  • ⅓ cup sour cream
  • ¼ cup fresh lemon juice
  • 2 tsp lemon zest
  • 1 tsp vanilla extract

For the Blackberry Buttercream:

  • 1 cup unsalted butter, softened
  • ¾ cup powdered erythritol
  • ½ cup fresh blackberries (mashed and strained if seedless is preferred)
  • 1 tsp lemon juice
  • 1 tsp vanilla extract

Instructions

  1. Preheat & Prep – Preheat oven to 325°F (163°C). Line two 8-inch cake pans with parchment paper and grease the sides.

  2. Mix Dry Ingredients – In a large bowl, whisk together almond flour, coconut flour, baking powder, baking soda, salt, and poppy seeds.

  3. Mix Wet Ingredients – In another bowl, whisk together eggs and sweetener until light and fluffy. Add melted butter, sour cream, lemon juice, lemon zest, and vanilla extract and stir until smooth.

  4. Combine – Slowly add the dry ingredients to the wet mixture, stirring gently. Let the batter rest for 5 minutes to thicken.

  5. Bake – Divide batter evenly between the cake pans and smooth the tops. Bake for 25-30 minutes or until a toothpick comes out clean. Let cool in pans for 10 minutes, then transfer to a wire rack.

  6. Make the Buttercream – Blend blackberries into a puree and strain if desired. Beat butter until creamy, then add powdered erythritol, blackberry puree, lemon juice, and vanilla extract. Mix until smooth. Chill for 10-15 minutes if too soft.

  7. Assemble the Cake – Spread a layer of frosting between the cakes, then cover the entire cake with the remaining buttercream.

  8. Chill & Serve – Let the cake chill for 30 minutes before slicing for the best texture.

Notes

  • Sweetener Swap – Any powdered or granulated keto-friendly sweetener will work. Avoid liquid sweeteners as they can affect texture.
  • Storage – Store in an airtight container in the fridge for up to 5 days or freeze slices for later.
  • No Poppy Seeds? – You can skip them or replace them with chia seeds for a similar texture.
  • Frosting Too Soft? – If the buttercream is too thin, chill it in the fridge before frosting the cake.

Please note: The recipe or ingredients shown in the video might vary slightly from what’s listed here. Use the video as an illustration, but for the best results, you might want to stick to the recipe provided in this article.

Nutrition

Find it online: https://www.wellnesswarrior.org/keto-poppy-seed-lemon-cake-with-blackberry-buttercream/