Lemon and Vanilla Buttercream Cupcakes

For my Sister Allison's shower, we served a vanilla cake, with vanilla buttercream frosting that had delicious layers of lemon curd inside and on top (From Cake Love - I highly recommend it, and all other things they do). I wanted to bring the same idea to cupcakes. So, although the title is confusing - these are Vanilla cupcakes spread with a layer of delicious sweet and tart Lemon Curd, and topped with Vanilla Buttercream Frosting.

Cupcakes

Ingredients
18 tablespoons (2 1/4 sticks) unsalted butter, at room temperature
3 cups sugar
6 extra-large eggs, at room temperature
1 cup sour cream, at room temperature
1 1/2 teaspoons pure vanilla extract
3 cups all-purpose flour
1/3 cup cornstarch
1 teaspoon kosher salt
1 teaspoon baking soda

*Jar of Lemon Curd - I don't have a recipe that I love, so i just bought a jar from William Sonoma.


Method
Heat the oven to 350 degrees F. Line muffin pans with paper liners.

Cream the butter and sugar in the bowl of an electric mixer fitted with the paddle attachment on high speed, until light and fluffy. On medium speed, add the eggs, 2 at a time, then add the sour cream and vanilla. Scrape down the sides and stir until smooth.

Sift together the flour, cornstarch, salt, and baking soda in a bowl. With the mixer on low speed, add the flour mixture to the butter mixture until just combined. Fill the cupcake liners to the top with batter. Bake in the center of the oven for 20 to 30 minutes, until a toothpick comes out clean. Cool to room temperature.


Vanilla Buttercream Frosting

Ingredients
4 Large eggs
1 cup sugar
2 t vanilla
pinch of salt
4 sticks UNSALTED butter - please, please make sure of this. I promise it makes a HUGE difference in this recipe. Cut each stick into quarters, and let stand at room temperature until it is soft, but still cool.

Method
Combine the eggs, sugar, vanilla and salt in the bowl of a standing mixer, and place the bowl over a pan of simmering water. (Like a double boiler, use your kitchen aid bowl if you have one, and don't let the bottom of the bowl touch the water)

Whisk gently but constantly, and heat the mixture until it is thin and foamy, and registers 160 on an instant-read thermometer.

Fit your bowl back onto your mixer and beat the egg mixture at medium-high speed until it is light and airy, and cooled to room temperature - about 5 minutes. Reduce the speed to medium, and the butter one piece at a time. The Mixture may begin to look curdled after you've added about 1/2 the butter, but it will smooth out. Once all the butter is added, increase the speed to high and beat 1 minute, until light and fluffy, and thoroughly combined.

Frosting the Cupcakes
I like to refrigerate my cupcakes over night before frosting them, but you can begin when they are cool if you wish. First, spread the tops of the cupcakes with a layer of Lemon Curd - about 1-2 teaspoons each, depending on your taste.

Scoop the buttercream into a pastry bag fitted with a large round tip (or just a ziplock with the corner cut off) and pipe on your frosting to your hearts content. And, I like to garnish with strips of Lemon peel, but you can leave them plain, or do yellow sprinkles - it's up to you.