Double Vanilla Cupcakes

Ingredients

• 1/2 cup whole milk
• 1/2 whole vanilla bean
• 1 1/2 cups + 2 tablespoons all-purpose flour
• 1/4 teaspoon kosher salt
• 1 1/4 teaspoons baking powder
• 1/4 cup sour cream
• 1 1/2 teaspoons vanilla extract
• 1/2 cup unsalted butter, room temperature
• 1 cup sugar
• 1 large egg
• 2 egg whites
• 1 1/4 cups powdered sugar
• 1/2 vanilla bean

Directions

1. Heat the oven to 350 degrees F. Tuck liners into the wells of a 12-cup muffin or cupcake tin, then set the pan aside. As the oven warms, split the vanilla bean and scrape out the seeds.
2. Add the milk, the scraped seeds, and the empty bean to a small saucepan. Warm it over medium heat for a few minutes, just until you see steam begin to rise. Keep it shy of a boil so the milk does not scald.
3. Take the pan off the heat, and let the vanilla sit in the milk as it cools. Once cool, lift out the pod. Rinse it, leave it to dry, and save it for another use.
4. In one bowl, whisk the flour with the baking powder and salt.
5. In a separate bowl, whisk the vanilla-steeped milk with the vanilla extract and sour cream.
6. Put the butter in the bowl of a stand mixer fitted with the beater attachment, and beat on medium speed for about 3 minutes. Add the sugar, then keep beating for about 3 minutes more, until the mixture is pale and fluffy.
7. Beat in the egg for 30 seconds. Add the egg whites one at a time, beating for 30 seconds after each addition. Run a spatula around the inside of the bowl.
8. On low speed, mix in half of the flour mixture just until it blends into the batter. Pour in all of the milk mixture and mix until combined. Add the remaining flour mixture last, mixing only until the batter comes together and no dry flour is showing. Do not get carried away here; over-mixing is not your friend.
9. Spoon the batter into the prepared liners, dividing it evenly. Bake at 350 degrees F for 18-20 minutes, until the tops are lightly golden. After 10 minutes, rotate the pan so everything bakes evenly. Keep an eye on them near the end, since they can go from done to overdone quickly.
10. Let the cupcakes rest in the pan for a few minutes, then carefully move them to a wire rack to cool completely.
11. Once the cupcakes are cool, make the frosting. Beat the butter for the frosting, gradually adding the powdered sugar. Scrape in the seeds from the vanilla bean, or add the vanilla extract if using, and beat it in. Frost each cupcake individually and serve. They are best the same day they are made, though they will keep fairly well for a few days in an airtight container at room temperature.