For 12 regular cupcakes:
1 3/4 cups cake flour
1 1/2 teaspoons baking powder
1/4 teaspoon salt
1/2 cup sour cream (I used full fat)
1/2 cup milk (I used whole)
2 large egg whites, at room temperature
113g unsalted butter, melted
1 cup granulated sugar
1 tablespoon fresh lemon juice
Zest of one lemon (about 2 teaspoons)
1/2 tsp vanilla extract
For the icing:
113g cream cheese
1/4 cup butter, softened
1 cup confectioners' sugar
2 tablespoons lemon juice
2 1/4 cups confectioners' sugar
For the cupcakes:
1. Preheat oven to 350 degrees (F). Line a 12 mould muffin tin with paper liners; set aside.
2. In a large measuring cup or bowl combine sour cream, milk, and egg whites; mix well to combine. Set aside.
3. In a large bowl or stand mixer fitted with the paddle attachment beat melted butter and sugar on medium speed until well combined; about 2 minutes.
4. Add lemon juice and lemon zest and beat for another minute on medium speed. Slowly add flour, baking powder and salt to the butter/sugar combination, beating until just combined.
5. Add in sour cream/milk/egg combo and beat on low until just combined. Finally, add vanilla extract until incorporated.
6. Over-mixing will result in a dryer/denser cake. Divide the cupcake batter evenly into the 12 molds, then place the pan in the oven.
7. Bake for about 22 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
8. Allow cupcakes to cool completely before topping with frosting.
For the icing:
9. Beat cream cheese and butter in a bowl until combined.
10. Beat in powdered sugar and lemon juice.
11. Beat in 2-1/4 to 2-1/2 cups more of powdered sugar till frosting is of spreading consistency.