2 C. cake flour
1 t. baking powder
2 t. kosher salt
12 T. unsalted butter, at room temp.
1 1/2 C. granulated sugar
1 T. vanilla
2 large egg whites, at room temp.
2 large eggs, at room temp.
3/4 C. whole milk, at room temp.
- Heat the oven to 350°F and arrange a rack in the middle. Line 2 (12-well) muffin pans with paper liners. Alternatively, coat the wells with butter; set aside.
- Combine flour, baking powder, and salt in a medium bowl and whisk to aerate and break up any lumps; set aside.
- Place butter in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-high speed until very light in color, about 3 minutes. Add sugar and vanilla seeds (if you’re using vanilla extract instead, you’ll add it later), and continue beating until mixture is airy, about 3 minutes.
- Scrape down the paddle and the sides of the bowl, turn the mixer to medium speed, and add egg whites one at a time, beating well after each addition. Then add eggs one at a time, beating well after each addition.
- Add milk (and vanilla extract, if you’re using it in place of seeds), and mix until combined (the mixture will look curdled, but it’s not). Scrape down the sides of the bowl. Reduce speed to low, add flour mixture, and mix until just combined, about 15 seconds.
- Fill the muffin wells about halfway, and bake cupcakes until golden brown and a toothpick inserted in the center comes out clean, about 18 minutes. Set the pans on a wire rack and let cool for 5 minutes. Remove cupcakes from the pans and let cool completely before frosting.
- Briefly stir together granulated sugar and water in a small saucepan and bring to a boil over medium-high heat. Continue cooking, without stirring, until mixture turns dark amber in color, about 6 to 7 minutes.
- Remove from heat and slowly add in cream and vanilla, stirring with a wooden spoon until completely smooth. Set aside until cool to the touch, about 25 minutes.
- Combine butter and salt in the bowl of a stand mixer fitted with the paddle attachment and beat on medium-high speed until light in color and fluffy, about 3 minutes. Reduce speed to low, add powdered sugar, and mix until completely incorporated.
- Turn mixer off and scrape down the sides of the bowl, then add caramel. Beat frosting on medium-high speed until airy and thoroughly mixed, about 2 minutes. Cover and refrigerate until stiff, about 45 minutes, before using.