buttermilk cupcakes with swiss meringue frosting

Ingredients

• 3 cups cake flour
• 1- 1/2 cups all-purpose flour
• 3/4 teaspoon baking soda
• 2-1/4 teaspoon baking powder
• 1-1/2 teaspoon sea salt
• 1 cup unsalted butter, at room temperature
• 2 tablespoons unsalted butter, at room temperature
• 2-1/4 cup sugar
• 5 - eggs, at room temperature
• 3 - egg yolks, at room temperature
• 2 cups buttermilk, at room temperature
• 2 teaspoons vanilla
• FROSTING
• 5 - egg whites
• 1 cup sugar
• 2 tablespoons sugar
• - pinch salt
• 1 pound unsalted butter, at room temperature
• 1-1/2 teaspoon vanilla