These cupcakes are our favorite!! They are delightfully soft and fluffy and are perfect with the creamy chocolate frosting.
Preheat oven to 350°F. Line a muffin pan with cupcake liners. Set aside.
In a medium-sized bowl, combine the flour, baking powder and salt. Set aside.
In a large bowl, use a handheld or stand mixer to beat the butter on medium speed for 2 minutes. Add the sugar, and beat on medium speed for 2 minutes. Add the eggs and egg yolk on at a time, mixing in between each addition. Add the vanilla, and mix until combined.
Add 1/3 of the flour mixture to the butter mixture, and mix on low speed until mostly combined. Add 1/2 of the buttermilk, and mix until mostly combined. Add another 1/3 of the flour mixture, and mix until mostly combined. Add the remainder of the buttermilk, and mix until mostly combined. Add the rest of the flour mixture, and mix until no lumps remain.
Scoop the cupcake batter into the tins, filling each about 2/3 full. Bake at 350°F for 15-16 minutes, or until a toothpick comes out clean. Allow the muffin tin to cool completely before baking the remaining 5 cupcakes. Allow the cupcakes to cool completely before frosting.
In a large bowl, use a handheld or stand mixer to beat the butter on medium speed for 2 minutes. Add the powdered sugar, cocoa powder, and milk, and mix until fully incorporated.
Once the cupcakes are fully cooled, they can be frosted (See Notes).
We used the Wilton 1M to decorate our cupcakes!
Make Ahead Tip: These cupcakes can be stored in an airtight container at room temperature for 2 days, then they can be transferred to the refrigerator and stored for 2-3 more days.