Caramel Cupcakes Ingredients For the cupcakes: 2 whole eggs 1 egg yolk 1 teaspoon pure vanilla extract 1/2 cup plus 2 tablespoons buttermilk, at room temperature 1 1/2 cups cake flour 1 cup sugar 2 1/4 teaspoons baking powder 1/4 teaspoon salt 1/2 cup (1 stick) unsalted butter, cut into 1/2 inch cubes, at