• Preheat the oven to 350°F (180°C). Line the muffin pan with cupcake liners.
• Place the sugar in the large mixing bowl of a stand mixer. Scrape the insides of the vanilla bean and place the beans in the sugar. Use your fingers to rub the vanilla bean into the sugar until it is dispersed throughout the sugar.
• In a small bowl combine the eggs, vanilla extract and 1/3 third of the sour cream and whisk the ingredients together. Cut the butter into 8 pieces.
• Add the all-purpose flour, the salt and the baking powder to the vanilla sugar in the mixing bowl. With the paddle attachment mix the dry ingredients on medium-low for 30 seconds to thoroughly combine the dry ingredients. Add the butter and remaining sour cream and mix on medium speed until the butter and sour cream are thoroughly incorporated and the mixture is creamy, about 1 minute. Be careful not to overmix. Scrape the sides and bottom of the bowl.
• Add the egg mixture in two batches, mixing on medium speed until the egg mixture is thoroughly incorporated. Scrape the sides and bottoms of the bowl and fold the batter by hand to ensure all the batter is mixed together.
• Divide the batter evenly between the 12 cups of the muffin pan, about 60 grams each. Each muffin tin should be about 2/3 full.
• Bake the cupcakes for 20-22 minutes until they are done. Remove the cupcakes from the oven and let them cool in the pan for 10 minutes before removing the cupcakes from the pan to a wire rack. Let the cupcakes to cool completely before frosting them.
• If making the cupcakes one day in advance before frosting them, store the cupcakes in an airtight container at room temperature.

How to Decorate the Cupcakes

• Using a Pastry Bag: Fit your pastry bag with an open star tip or your favorite decorating tip and fill it with frosting. Starting at the outside edge of the cupcake, pipe frosting in a swirl with the tip about 1/4" to 1/2" above the cupcake, exerting even pressure on the bag continuously. Finish the swirl in the center of the cupcake by removing the pressure and lift up the tip slightly as you near the center. If you’re new to decorating cupcakes it may take some practice.
• Using a Knife or Offset Spatula: Use a spoon to add about 2 tablespoons of buttercream to the cupcake. Use the back of a spoon, a non-serrated butter knife, or a small offset spatula to spread the buttercream to the edge. While pressing down on the frosting slightly, move your spoon or knife in a spiral pattern from the outside edge of the cupcake to the center of the cupcake, to create a pretty spiral or swoop. 

Storage

• The unfrosted cupcakes are good at room temperature in an airtight container for up to two days. Once the cupcakes are frosted they should be consumed with one day.