Preheat oven to 350°F. Line a cupcake pan with cupcake liners. Set aside.
In a medium bowl, whisk together the flour, salt, and baking powder. Set aside.
With a hand mixer or stand mixer fitted with a paddle attachment, cream butter on high for 2 minutes. Add in sugar and mix until smooth and creamy, about 2 more minutes.
Add egg and egg white one at a time on low speed until incorporated. Mix in the vanilla extract and the seeds of the vanilla bean.
Slowly add half of the dry ingredients to the wet ingredients. When mixed, add in half of the milk. Add the rest of the dry ingredients and the rest of the milk until no lumps remain.
Pour the batter into the cupcake liners, only filling about halfway. Bake for 18-20 minutes or until a toothpick inserted into the center of the cupcake comes out clean.
Let the pan cool on a wire rack for 10 minutes. Take the cupcakes out of the pan and place on a wire rack to finish cooling, about an hour. Cupcakes must be completely cooled before frosting!
Vanilla Buttercream Icing
With a hand mixer or stand mixer fitted with a paddle attachment, cream butter on high until smooth. Add in confectioner's sugar, 1 cup at a time, alternating with tablespoons of half and half until desired consistency. Add in vanilla extract.
Using a piping bag, pipe frosting onto cooled cupcakes and enjoy!