In a small bowl, combine sugar and seeds from the vanilla bean.
In a medium-sized mixing bowl or bowl of a stand mixer, mix together cake flour, baking powder, baking soda, and salt.
Add the vanilla bean sugar mixture to the dry ingredients and mix until well combined
Add butter and mix on medium-low speed for three minutes. (You'll end up with a very fine crumb texture.)
In a small mixing bowl, whisk together eggs, sour cream, oil, and vanilla extract until smooth.
Add the egg mixture to the flour mixture and beat on medium speed until just combined.
Slowly add milk and mix on low speed until just combined. (The batter will be liquid.)
Fill cupcake liners just over 1/2 full.
Bake for 15 minutes. (They are done when a toothpick comes out clean. The cupcakes should appear white with specks of vanilla bean. They should not turn a golden brown.)
Remove them immediately from the tins to cool. Add icing or filling once cool.
RECIPE TIPS
Here is a link to the original recipe on Stef's blog, The Cupcake Project.BEWARE: The calories noted DO NOT INCLUDE icing. The Cream Cheese Icing we used can be found in our Banana Cake post.