1. Preheat oven to 350 degrees F. Line two muffin pans with white cupcake liners. Recipes makes 15 cupcakes.
2. In medium mixing bowl, add cake flour, baking powder, baking soda, salt, whisk together, set aside. Do not scoop or pack flour in measuring cup, instead spoon and level in cup for accuracy.
3. Using a stand or handheld mixer with beater attachments, cream together butter and sugar at high speed in mixing bowl until smooth and creamy, about 2 minutes. Butter will begin to turn lighter in color.
4. Add sugar gradually, beat until creamed together about 2 minutes. Scrape down sides and bottom of bowl with rubber spatula as needed.
5. Add room temperature egg whites, vanilla extract, vanilla bean, beat on medium speed until combined. Scrape down sides and bottom of bowl with rubber spatula.
6. Add sour cream and milk or yogurt with water to batter, beat to combine. Add half of the flour mixture, this time fold in the ingredients by hand with rubber scraper or very low speed on mixer. Add remaining flour, stir just to combine, be careful not to over mix batter.  Batter will be thick.
7. Using a spring loaded ice cream scoop or 3 tablespoons of batter to each cupcake liner filling 2/3 full. This will give you a rounded top with out overflowing in cupcake pan.
8. Bake cupcakes 19 -20 minutes in center of preheated 350 degree oven. Remove from oven after baking and allow to cool before filling and frosting.

Filling Cupcakes: Using a knife or the end of a large piping tip, hollow out the center of the cooled cupcake. Keep top part of cupcake to use as a plug after filling. Fill piping bag with no tip with Nutella. Cut of end of piping bag, pipe Nutella into center of cupcake. Top with reserved cupcake piece. Frost with chocolate buttercream.

Make Chocolate Buttercream frosting.

Cream softened butter in medium mixing bowl, add vanilla and salt, whip until smooth and creamy. Add confectioners sugar and cocoa together, hand stir this mixture together before adding to butter. Add to butter mixture, little bit of cream, mixing on medium speed until frosting is smooth and creamy. It will be a thick frosting but soft enough to pipe. Fill disposable piping bag fitted with Tip #8B or #1 M. I used #8B for the swirl.  Garnish with Cherry heart jelly beans or valentine sprinkles.