Preheat your oven to 375°F and line your cupcake pan with 6 liners.

In a medium bowl combine butter and sugar and using a handheld electric mixer, cream together until light and fluffy, 1 to 2 minutes.

Add egg white and vanilla. Beat on medium until smooth.

Add 1/4 cup (30g) of the flour, baking powder, and salt. And mix on low until incorporated.

Mix in milk on low. Add remaining 1/4 cup of flour and mix on medium until well-mixed and smooth. Divide batter between prepared cupcake cups, filling just under 2/3 full. This should make exactly 6 cupcakes. Bake for 17 to 20 minutes, until a toothpick inserted into the center of the cupcakes comes out clean or with just a couple dry crumbs.

Transfer to a cooling rack when the cupcakes are cool enough to handle and cool completely before frosting.

In a medium bowl, combine butter, powdered sugar, milk or cream, vanilla, and salt. Beat until frosting comes together, adding milk by the 1/2 teaspoon as necessary.