Lemon Blackberry Cake
Lemon Blackberry Cake features fluffy lemon layers filled with homemade blackberry curd and frosted with whipped blackberry buttercream. This bright and tangy cake is perfect for spring, summer, and any lemon-lover in your life.
Equipment
- Kitchen scale (please weigh your ingredients)
- Stand mixer (or large mixing bowl with an electric mixer)
- medium bowl for mixing dry ingredients
- Small saucepan for making curd/jam
- Lemon zester
- Manual juicer
- 3 8-inch round cake pans
- Parchment paper rounds
- Cake decorating knife
- Cake rounds (to place the cake. You can use a large plate if you'd prefer.)
- Piping bag (optional; I didn't use one.)
- Icing tip of choice (optional; I didn't use one.)
- KitchenAid Fruit and Vegetable Strainer (optional; you can blend/smash the berries and strain through a fine mesh strainer instead)
Ingredients
Blackberry Curd
- 12 oz fresh blackberries around 3 cups
- 1 large egg
- 2 egg yolks
- 57 g unsalted butter ¼ cup
- 100 g granulated sugar ½ cup
- 22.5 g lemon juice 1.5 tablespoons
Lemon Cake
- 300 g granulated sugar 1 ½ cups
- 170 g unsalted butter room temperature (¾ cup)
- 170 g sour cream ¾ cup
- 9 g vanilla extract 2 tsp
- 8 g lemon zest 2 tablespoons from 2 lemons
- 6 egg whites (around 30g each or 180g total)
- 300 g all-purpose flour 2 ½ cups
- 18 g baking powder 4 tsp
- ½ teaspoon salt
- 180 ml milk ¾ cup
- 59 ml water ¼ cup
Blackberry Buttercream
- 8 oz fresh blackberries 300g, 2 cups
- 90 g fresh lemon juice 6 tablespoons
- 25 g sugar 2 tablespoons
- 900 g powdered sugar about 9-10 cups
- 452 g unsalted butter room temperature (2 cups)
Instructions
Make the Curd
- Make the Blackberry Puree: Blend the blackberries until smooth, then press the puree through a fine mesh strainer using a silicone spatula or spoon until you have ¾ cup of seedless puree. Discard the seeds and pulp.(For a faster process, I love using the KitchenAid fruit and vegetable strainer—it purees and strains in one step!)12 oz fresh blackberries
- Reduce the Puree: Pour the strained puree into a small saucepan and heat over low to medium heat, stirring often to prevent scorching. Let it simmer until it thickens and reduces to just over ⅓ cup—it should be very thick and jammy.
- Whisk in Remaining Ingredients: Add the lemon juice and sugar to the reduced puree and whisk until combined. Then quickly whisk in the egg and egg yolks, making sure to add them last to avoid scrambling—keep the mixture moving as you go.1 large egg, 100 g granulated sugar, 22.5 g lemon juice, 2 egg yolks
- Cook the Curd: Reduce the heat to low and continue stirring until the sugar is fully dissolved. Add the butter one tablespoon at a time, stirring until each piece is fully melted before adding the next.57 g unsalted butter
- Finish and Chill: Continue cooking and stirring the curd until it’s thick enough to coat the back of a spoon. You’ll know it’s ready when you can drag a spoon or spatula through it and the line holds without filling back in.
- Strain and Chill: For the smoothest texture, strain the curd one more time to catch any small lumps or cooked egg bits. Cover with plastic wrap (pressing it directly against the surface) and refrigerate until completely chilled.
Make the cake
- Zest the Lemons: Zest 2 lemons until you have about 2 tablespoons (or roughly 30g) of zest, then set it aside.8 g lemon zest
- Prep the Pans and Oven: Preheat your oven to 350°F. Line three 8-inch cake pans with parchment paper and lightly grease the sides—I love using precut parchment rounds for easy prep.
- Cream the Butter and Sugar: In a large bowl, beat the butter and sugar together until light, fluffy, and pale in color—this should take about 3–4 minutes with a stand or hand mixer.300 g granulated sugar, 170 g unsalted butter
- Mix in Wet Ingredients: Add the vanilla extract, sour cream, and lemon zest to the bowl and mix until everything is fully combined and smooth.170 g sour cream, 9 g vanilla extract, 8 g lemon zest
- Add Egg Whites: Gradually add the egg whites in two or three additions, mixing well after each and scraping down the sides of the bowl to keep the batter uniform and silky.6 egg whites
- Combine Milk and Dry Ingredients: In a small bowl or measuring cup, stir together the milk and water. In a separate bowl, whisk together your dry ingredients (like flour, baking powder, and salt).300 g all-purpose flour, 18 g baking powder, 180 ml milk, 59 ml water, ½ teaspoon salt
- Mix the Batter: Add half of the dry ingredients to the batter and mix just until incorporated. Pour in the milk and water mixture, mix again, then add the remaining dry ingredients and mix until smooth—don’t forget to scrape the bowl one last time.
- Bake the Cakes: Divide the batter evenly between your prepared cake pans and bake for 23–25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs but no wet batter.
Make the Buttercream
- Make the Blackberry Reduction: Add the blackberries, sugar, and lemon juice to a saucepan over medium heat. Once the mixture is warm, mash the blackberries and let it simmer for about 10 minutes, stirring occasionally to prevent sticking.8 oz fresh blackberries, 90 g fresh lemon juice, 25 g sugar
- Strain and Chill: Pour the mixture through a fine mesh sieve into a bowl, pressing out as much liquid as possible and discarding the seeds and solids. Cover and chill the reduction in the fridge until fully cooled, about 2 hours.
- Make the Buttercream: In a stand mixer with a paddle attachment or a large bowl with a hand mixer, cream the room temperature butter on medium speed for 3-5 minutes, until smooth and fluffy. With the mixer on low, gradually add the confectioners’ sugar, then mix in the blackberry reduction one tablespoon at a time until the frosting reaches your desired color and consistency (I typically use about ¼ cup).452 g unsalted butter
- Adjust if Needed: If the frosting is too thick, add 1 to 2 tablespoons of milk or water to thin it out. Use immediately for the best texture and flavor.
Assemble the cake
- Level the cake layers: If needed, use a serrated knife to level the tops of each lemon cake layer so they stack evenly.
- Add a base of buttercream: Place the first cake layer on a cake stand or serving plate. Spread a thin, even layer of blackberry buttercream over the top—this will act as a barrier to keep the curd from soaking into the cake.
- Add the Curd Filling: Spoon blackberry curd on top of the buttercream and gently spread it out, staying about ½ inch away from the edges to prevent overflow.
- Repeat the Layers: Place the second cake layer on top and repeat the process: a thin layer of buttercream, followed by a layer of blackberry curd. Top with the final cake layer.
- Crumb Coat the Cake: Apply a thin layer of buttercream over the entire cake to catch any crumbs. Chill the cake in the fridge for 20–30 minutes to set the crumb coat.
- Frost the Cake: Once chilled, cover the cake with the remaining blackberry buttercream—use an offset spatula to smooth the top and sides.
- Add the Swirled Curd: Spoon small dollops of the leftover blackberry curd randomly over the frosted cake. Use the back of a spoon or a small spatula to gently swirl the curd into the buttercream for a marbled effect.
- Finish with Lemon Zest: Sprinkle fresh lemon zest over the top of the cake just before serving for a bright, citrusy finish.
Notes
- Instead of blending/mashing and straining the berries, you can also use the KitchenAid fruit and vegetable strainer—it purees and strains in one step!
Nutrition
Calories: 1004kcalCarbohydrates: 134gProtein: 7gFat: 51gSaturated Fat: 31gPolyunsaturated Fat: 2gMonounsaturated Fat: 13gTrans Fat: 2gCholesterol: 182mgSodium: 301mgPotassium: 116mgFiber: 2gSugar: 111gVitamin A: 1571IUVitamin C: 2mgCalcium: 146mgIron: 2mg
Tried this recipe?Let us know how it was!