- 2 large eggs, separated
- 1 3/4 cup sifted cake flour
- 2 teaspoons baking powder
- 1/4 teaspoon salt
- 1/2 cup unsalted butter at room temperature
- 1 cup sugar, divided
- 1/2 teaspoon vanilla extract
- 1/2 teaspoon almond extract
- 1/2 cup buttermilk
- 1/8 teaspoon cream of tartar
for the frosting:
- 1/4 cup sugar
- 2 tablespoons water
- 1/4 cup heavy cream
- 1 teaspoon Fleur de Sel, plus more for garnish
- 1 teaspoon vanilla
- 3/4 cup unsalted butter, softened
- 2 cups powdered sugar
Preheat oven to 350 degrees. Line (12) muffin cups or mini cupcake pans with paper liners.
Separate eggs, placing yolks in one bowl and the whites in another. Cover both bowls with plastic wrap and allow eggs to come to room temperature, about 30 minutes.
In a small mixing bowl, whisk together the flour, baking powder and salt. In a large mixing bowl, beat the butter until soft. Add 3/4 cup of the sugar and beat until light and fluffy (about 2 to 3 minutes). Add egg yolks, one at a time, beating after each addition. Scrape down the sides of the bowl making sure everything is incorporated. Add vanilla and almond extracts; beat until combined.
With the mixer on a low speed, alternately add the flour mixture and milk in three additions, beginning and ending with the flour. Set aside.
To prepare the egg whites, beat on medium speed with an electric mixer until foamy. Add the cream of tartar. Increase speed to high and beat until soft peaks form. Gradually add the remaining 1/4 cup sugar and continue to beat until stiff peaks form. This is when the eggs really hold a shape, like a bird’s beak.
With a rubber spatula, gently fold a little of the whites in the batter. Then fold in the remaining whites just until combined. Over-mixing will cause the batter to deflate, which you definitely want to avoid.
Pour or scoop the batter into cupcake pans until they are 2/3 full. Bake for 17-20 minutes, or until a cake tester comes out clean. Remove from oven and let cool in pans for 5 minutes. Remove cupcakes from pans and let cool on a wire rack.
Combine water and sugar for frosting in a small saucepan, swirling to combine. Bring to a boil over medium-high heat, watching closely. Continue cooking without stirring, until mixture turns dark amber in color, about 6 to 7 minutes. It will turn this color VERY fast, so as soon as you see this color remove it from the stovetop. It can burn if you leave it for even seconds too long. Slowly and carefully add in cream as mixture will bubble and steam up (and can burn you). Stir with a wooden spoon until completely smooth; add salt. You may need to place it back on the stove over low heat to ensure sugar and cream are combined (and that sugar is not just hardened in the bottom). Set aside until cool to the touch, about 25 minutes. Add vanilla and stir.
In a medium mixing bowl, beat butter on medium-high speed until light in color and fluffy, about 3 minutes. Reduce speed to low and add powdered sugar. Mix until completely incorporated. Add caramel. Beat frosting on low to combine, then increase to medium-high and beat until airy and thoroughly mixed, about 2 minutes. Immediately frost cooled cupcakes with piping bag fitted with a large round tip. Garnish each cupcake with a small pinch of Fleur de Sel. Refrigerate until ready to use, taking out about 30 minutes before eating.