I've made a faux Swiss buttercream and last year for my birthday I made a real Swiss buttercream. This week I made a lemon Swiss buttercream and it is amazing.
I've had lemon cupcakes on my list of things to make for about six months. Finally I decided I was going to make a batch. The cake part has a fantastic crumb. Light, lemony, perfect. Then I made the frosting. It seemed not as hard as it did the first I made Swiss buttercream. It is a little scary after you add the butter to the meringue and it looks like a mess. It gets better. I swear. Give it time. Let it do its thing.
I didn't have lemon extract in the house so I used fresh lemon juice in both the cupcakes and the frosting. Worked out just fine. Be sure to use the lemon zest because it adds quite a bit of the lemon flavor.
Have fun with these!!
Source: Humble Gourmand
Yield: One dozen
1 ¼ cups all-purpose flour
¼ tsp. kosher salt
½ tsp. baking powder
¼ pound unsalted butter, at room temperature
1 cup sugar
zest of 2 lemons
2 large eggs
½ cup buttermilk
Preheat oven to 350F.
Combine butter, sugar, and lemon zest in large mixing bowl. Using an electric mixer beat on medium-high speed until the mixture is fluffy and much lighter in color. Combine the flour, salt, and baking powder in a bowl. In a third, small bowl, combine the buttermilk and lemon extract.
Add the eggs one at a time to the mixer, making sure to fully incorporate the first egg before adding the second. Alternate adding the flour mixture and buttermilk in the following order: add 1/3 of the dry ingredients, 1/2 of the wet, another third of the dry, the rest of the wet, and the rest of the dry. Mix until just combined and finish with a spatula.
Bake in the top third of the oven for about 20 minutes or until the tops are slightly golden and a toothpick inserted into the center of a cupcake comes out clean. Let cool completely before topping with the lemon buttercream.
Lemon Buttercream Frosting
7 egg whites
Pinch cream of tartar
2 c. sugar
2 Tbsp. light corn syrup
½ c. water
1 lb. unsalted butter at room temperature
2 tsp. lemon extract
Yellow food coloring (optional)
Place egg whites and cream of tartar in the bowl of an electric mixer fitted with the whisk attachment. Beat on low speed. Add sugar, corn syrup, and water to a pot and swirl or mix with a spoon so that the sugar has the consistency of wet sand and all of the granules are moistened.
Cook the sugar on high to 235F. At this stage, which candymakers call the soft ball stage, most of the moisture gets cooked out of the sugar. Immediately add the cooked sugar to the egg whites, which should be foamy at this point. Turn the mixer speed to high and whip the meringue to a medium peak. Add the butter in small clumps (about 1½” cubes) and whip until the mixture becomes light and fluffy, and holds together. Add the lemon extract and food coloring if using and whip to combine.