White Cake with Lemon Curd and Mascarpone Frosting

This cake started with lemon curd.  I really really wanted to try this microwave lemon curd from King Arthur Flour.  So I did, and it worked out really well.  It was fairly quick and easy, and the flavor is super bright tart and lemony.  So then.  I have 2 cups of lemon curd in the fridge.  What to do.  We decided to make a cake.  Sort of by chance, I found a beautiful white cake recipe also on King Arthur Flour. It. Was. Incredible.  The batter was so smooth and satiny, I just knew it was going to bake up delightfully.  Instead of using vanilla extract, I used lemon with the almond and the flavor was really nice.  Not super almond, not super lemon, but a fantastic combination.  Finally, I topped this crazy cake off with some mascarpone frosting.  Enough said.  The tart lemon curd was a perfect compliment to the fluffy white cake and sweet and rich frosting.  Definitely a success! Note: You will need to make the lemon curd the day before you assemble the cake. 

White Cake with Lemon Curd and Mascarpone Frosting

Lemon Curd:
1 cup fresh lemon juice
1 cup granulated sugar
1/2 cup butter
2 eggs

White Cake:
2 3/4 cups (326g) cake flour
1 2/3 cup (333) granulated sugar 
1 Tablespoon baking powder
3/4 teaspoon salt
3/4 cup (12 Tablespoons, 170g) butter, room temperature
4 large egg whites
1 egg
1 cup (227g) full fat vanilla yogurt or 1 cup (227g) whole milk
1 teaspoon lemon extract
1 teaspoon almond extract

Mascarpone Frosting:
2 sticks butter, room temperature
8 ounces mascarpone cheese
1/2 teaspoon vanilla extract
1 vanilla bean, split and seeds scraped out
4 cups powdered sugar

For the lemon curd, combine the lemon juice, sugar, butter and eggs in an 8 cup glass bowl or measuring cup.  If you use a smaller bowl, your curd may boil over in the microwave.  Microwave in 1 minute increments, stirring the lemon curd well after each.  When the lemon curd thickens and coats the back of a spoon it is done.  The temperature should be at least 185F.  This will take between 4 and 10 minutes.  

Stir the lemon curd, transfer to a container with a lid and refrigerate until the curd is chilled and firm.Preheat the oven to 350F.  Grease and flour two 8-inch round cake pans.

Place the cake flour, sugar, baking powder, and salt in the bowl of a stand mixer and mix on low speed to blend.  Add the butter and mix until incorporated and the mixture looks like damp sand.  Beat in the egg whites, one at a time, beating well after each addition, followed by the whole egg, beating well until incorporated.  Make sure that you are scraping down the sides of the bowl as you go.

Combine the yogurt (or milk) and extracts in a small bowl.  Add one third of the mixture to the batter and beat for 1 to 2 minutes, scraping the sides and bottom of the bowl.  Add another third then beat for 1 to 2 minutes, followed by the remaining third and beat for 1 to 2 minutes.

Pour the batter into the prepared pans and smooth the tops.  Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean.  Remove cakes from the oven and let cool for several minutes.  Turn the cakes out of the pans and cool completely on a cooling rack.

For the frosting, cream together the butter and mascarpone cheese until smooth.  Beat in the vanilla extract and vanilla bean seeds.  Beat in the powdered sugar, one cup at a time, until incorporated.  Continue to beat until light and fluffy.

To assemble the cake, trim the domes off the tops of the cakes if necessary.  Cut each cake layer in half horizontally, giving you 4 thinner cake layers.  Place one cake layer on a serving plate and spread about 1/3 cup of lemon curd on top.  Place the second cake layer on top.  Spread another 1/3 cup of lemon curd on top and place the third cake layer on top.  Spread another 1/3 of the lemon curd on top and place the final cake layer on top of the stack. You will have leftover lemon curd, just store it for another use.  Frost the top and sides of the cake with the mascarpone frosting.  Makes 16 servings.

Enjoy!  -Cardamommy