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Lemon Layer Cake with Mascarpone Buttercream

Lemon Layer Cake with Mascarpone Buttercream

A lemon layer cake filled with lemon curd and lightly frosted with mascarpone buttercream. It’s the perfect cake to welcome the the start of Spring.
Yield: three layer 8-inch cake
Prep Time: 50 mins
Cook Time: 30 mins
Total Time: 1 hr 20 mins
Course: cake
Cuisine: American
Keyword: lemon cake, lemon curd cake, mascarpone buttercream, lemon layer cake
Servings: 12 slices
Author: Maryanne Cabrera

Ingredients

Lemon Cake:

  • 2 ¼ cups all-purpose flour
  • 1 teaspoon baking powder
  • 1 teaspoon baking soda
  • ½ teaspoon kosher salt
  • ¾ cup unsalted butter, softened
  • 1 ¼ cup granulated sugar
  • 3 large eggs, room temp
  • cup sour cream, room temp
  • cup whole milk, room temp
  • 5 Tablespoons fresh squeezed lemon juice
  • 1 Tablespoon finely grated lemon zest
  • ¼ cup store-bought, high-quality lemon curd (to fill cake)

Mascarpone Buttercream:

  • 1 ¼ cup unsalted butter, softened
  • 4 ½ cups confectioners' sugar
  • 1 teaspoon finely grated lemon zest
  • 2 teaspoons fresh squeezed lemon juice
  • ¼ teaspoon kosher salt
  • 8 oz mascarpone cheese

Instructions

Lemon Cake:

  • Preheat oven to 350° F. Line three 8-inch cake round pans with parchment paper. Lightly grease and set aside.
  • In a large bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
  • In the bowl of a stand mixer fitted with a paddle attachment, cream butter. Add sugar and whip until smooth. Add eggs and continue to mix on medium speed until incorporated. Add sour cream and mix. Scrape down bowl as needed to ensure thorough mixing.
  • Add flour mixture in three additions, alternating with milk. Begin and finish with flour mixture. Add lemon juice and lemon zest and mix until well incorporated.
  • Divide batter evenly among the three prepared cake pans. Level batter using a mini offset spatula, or the back of spoon. Bake for 30-35 minutes until a toothpick inserted in center of cake comes out clean. Let cake cool in pan for 5 minutes, then run a mini offset spatula around the cake and unmold. Let cake cool to room temperature on wire rack.

Mascarpone Buttercream:

  • In the bowl of a stand mixer fitted with a paddle attachment, beat butter, confectioners' sugar, lemon zest, lemon juice, and salt until smooth. Scrape down bowl as needed to ensure thorough mixing. 
  • Add mascarpone and mix until just combined. If buttercream is too thick, add 1 tablespoon of milk (half & half, or heavy cream) and mix until smooth. 

Assembly:

  • Fit a decorating bag (piping bag) with a small round tip. Fill the bag with about ½ cup of buttercream. Set aside.
  • If necessary, level cake layers. Place one cake round on a cake turntable. Spread a thin layer of buttercream on cake using a small offset spatula. Using the filled piping bag, pipe a small border of mascarpone buttercream along the perimeter of the cake round. This will serve as a barrier when you filled the cake with lemon curd.
  • Add about two tablespoons of lemon curd to fill the buttercream boundaries. Place second cake layer on top. Repeat filling cake layer with buttercream and lemon curd. Place the final third layer on top. This layer will not have lemon curd
  • Spread buttercream around the cake to create a "crumb coat" layer to seal in any crumbs. Chill cake in the fridge for 15-20 minutes to set frosting. If desired, generously coat the chilled cake with additional buttercream. Chill cake if not serving immediately. 
  • Use an 18 mm star piping tip to pipe a border along the top layer of the cake. Decorate cake with confetti sprinkles as desired. Let chilled cake sit at room temperature for at least 20 minutes before serving to allow cake to soft. 

Notes

Make Ahead Cake:
  • Lemon cake can be baked ahead of time. Cool to room temperature before wrapping in plastic wrap.
  • Can be stored in the freezer and used at a later time. Simply allow cake to defrost at room temperature before use.