Preheat Oven to 325 degrees. Line 24 cupcake tins with paper liners.
Add cake mix. flour and sugar to bowl of electric mixer and whisk until combined
Add eggs, milk, oil and sour cream to the flour mixture and beat on low for 2 minutes.
Carefully slice open the vanilla bean and scrape seeds out with dull edge of a paring knife. Add the beans to the batter and mix to combine thoroughly.
Pour batter evenly into the prepared cupcake liners, filling each about 2/3 full.
Bake in preheated oven for 17 minutes, or until toothpick comes out clean. Allow to cool completely before frosting.
Frosting
While the cupcakes are cooling prepare the frosting.
Add shortening, 4 cups of the confectioners sugar and 1/2 cup milk or cream to the bowl of electric mixer and carefully increase speed to medium high. Whip for 2-3 minutes.
Add remaining confectioners sugar one cup at a time, bearing well between each addition.
Scrape seeds from the vanilla bean and add to the frosting, beating until well combined.
Spread or pipe frosting onto cooled cupcakes.
Decorate to your liking.
Notes
Store leftovers in an airtight container for up to 3 days, or freeze before frosting. Bring to room temperature before frosting.