Lemon Blueberry Mascarpone Cake
A bright, showstopping layer cake — three lemon layers stacked with jammy blueberry compote filling and clouds of mascarpone buttercream frosting. Tangy, creamy, and just the right amount of sweetness.
Equipment
- Kitchen Scale
- Stand Mixer (with paddle and whisk attachment)
- Zester or grater
- 3 tablespoon cookie scoop (optional )
- 3 8-inch cake pans
- Knife for icing
- small saucepan
- Pastry brush
- Pastry bag with large round tip, optional
Ingredients
Lemon Cake
- 360 grams all-purpose flour
- 2 ½ teaspoons baking powder
- ½ teaspoons baking soda
- 1 teaspoons fine sea salt
- 226 grams unsalted butter room temperature
- 350 grams granulated sugar
- 3 tablespoons lemon zest about 3–4 large lemons
- 4 large eggs room temperature
- 60 milliliters fresh lemon juice
- 2 teaspoons pure vanilla extract
- 180 grams full-fat sour cream room temperature
- 120 milliliters whole milk room temperature
Blueberry Compote
- 200 grams blueberries fresh or frozen
- 2 tablespoons granulated sugar
- 1 tablespoons lemon juice
Lemon Mascarpone Buttercream Frosting
- 226 g mascarpone cheese room temp (8 ounces)
- 226 g unsalted butter softened (1 cup)
- 680 g powdered sugar about 5 ½ cups
- 2 teaspoons pure vanilla extract
- 1 tablespoon fresh lemon zest
- 30-45 milliliters fresh lemon juice 2–3 tablespoons
- ½ teaspoon fine salt
- 30–60 milliliters heavy cream 2–4 tablespoons, if needed
- 100 grams fresh blueberries for garnish
Lemon Syrup (optional)
- 100 g water
- 100 g sugar
- 30 g fresh lemon juice
- ½ teaspoon vanilla extract
Instructions
- Prep: Preheat your oven to 350°F. Grease three round cake pans, line the bottoms with parchment paper, and grease again. In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and fine sea salt. Set aside.360 grams all-purpose flour, 2 ½ teaspoons baking powder, ½ teaspoons baking soda, 1 teaspoons fine sea salt
- Make the lemon sugar: In the bowl of a stand mixer, combine the granulated sugar and lemon zest. Use your fingertips to rub the zest into the sugar until fragrant and slightly damp. This blooms the lemon oils and makes a huge difference in flavor.350 grams granulated sugar, 3 tablespoons lemon zest
- Cream butter and sugar: Add the room temperature butter to the lemon sugar. Beat on medium-high until very pale, fluffy, and noticeably increased in volume. Scrape down the bowl.226 grams unsalted butter
- Add eggs and flavor: With the mixer on medium, add the room temperature eggs one at a time, beating well after each addition. Mix in the vanilla extract and fresh lemon juice. The batter may look slightly curdled — that’s okay.4 large eggs, 60 milliliters fresh lemon juice, 2 teaspoons pure vanilla extract
- Combine wet and dry: Whisk together the room-temperature sour cream and whole milk in a small bowl. With the mixer on low, alternate adding the flour mixture and the sour cream mixture, beginning and ending with the flour mixture. Mix just until combined. (we do this to prevent flour clumps). Do not overmix.180 grams full-fat sour cream, 120 milliliters whole milk
- Bake: Divide the batter evenly between the prepared pans. Bake until the tops are set, the edges pull away slightly from the pans, and a toothpick inserted in the center comes out with just a few moist crumbs.
- Cool the cakes: Let the cakes cool in the pans briefly, then turn them out onto a wire rack and cool completely before frosting.
- Make the blueberry compote: In a small saucepan over medium heat, combine the fresh or frozen blueberries, granulated sugar, and lemon juice. Cook, stirring occasionally, until the berries burst and the mixture thickens to a jammy consistency. Transfer to a bowl and refrigerate until completely cold.200 grams blueberries, 2 tablespoons granulated sugar, 1 tablespoons lemon juice
- Make the mascarpone frosting: In a stand mixer fitted with the whisk attachment, beat the mascarpone and room-temperature butter on medium until smooth. Add the powdered sugar, vanilla extract, and salt, then mix on low until incorporated. With the mixer running on medium, slowly stream in the cold heavy cream. Increase the speed to medium-high and whip until the frosting holds stiff, billowy peaks. Watch carefully, because mascarpone frosting can overwhip and turn grainy. Stop as soon as it holds its shape.226 g mascarpone cheese, 226 g unsalted butter, 680 g powdered sugar, 2 teaspoons pure vanilla extract, 1 tablespoon fresh lemon zest, 30-45 milliliters fresh lemon juice, ½ teaspoon fine salt, 30–60 milliliters heavy cream
- Make the lemon syrup (if using): Add the water and sugar to a small saucepan over medium heat. Stir until the sugar dissolves completely. Remove from the heat and stir in the lemon juice, lemon zest, and vanilla if using. Let cool completely before brushing onto cake layers.100 g water, 100 g sugar, 30 g fresh lemon juice, ½ teaspoon vanilla extract
- Assemble: Level your cake layers if needed. Place the first layer on a cake board or plate. Brush with lemon syrup if using. Pipe a ring of frosting around the outer edge as a dam, then spread the blueberry compote in the center. Repeat with the second layer. Place the third layer on top. Apply a thin crumb coat of frosting all over and refrigerate until set.
- Final frost and finish: Apply a generous final coat of mascarpone frosting. Reserve extra frosting in the fridge for re-frosting after cutting for photos. Finish with swoopy, textured swirls. Garnish with fresh blueberries, lemon slices, or edible flowers. Refrigerate until ready to serve, then let the cake sit at room temperature briefly before slicing for the best texture.100 grams fresh blueberries
Notes
Keep the compote out of the frosting: The blueberry compote stays as the filling between layers only — it adds moisture that can destabilize whipped mascarpone over time. The clean white frosting also gives you gorgeous contrast against the purple filling when you cut into it.
Don't over-whip the mascarpone frosting: Once it reaches stiff peaks, stop. Over-whipped mascarpone turns grainy and can break — it happens fast, so watch it closely in the last minute of whipping.
Powdered sugar range: 260g gives a lightly sweetened, very tangy mascarpone frosting. 300g is more balanced and sweeter. Start at 280g and taste — adjust before adding the cream.
Room temperature ingredients matter for the cake batter: cold butter and eggs will give you a lumpy batter. Set everything out 1–2 hours early.
Make-ahead: Cake layers can be baked 2 days ahead and wrapped at room temperature, or frozen for up to a month. The compote can be made 3 days ahead. Make the frosting the day you assemble — mascarpone frosting doesn't hold as well overnight.
Nutrition
Calories: 693kcalCarbohydrates: 94gProtein: 6gFat: 34gSaturated Fat: 21gPolyunsaturated Fat: 1gMonounsaturated Fat: 7gTrans Fat: 1gCholesterol: 125mgSodium: 354mgPotassium: 102mgFiber: 1gSugar: 74gVitamin A: 1085IUVitamin C: 7mgCalcium: 100mgIron: 1mg
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