1cup(226 g or 2 sticks) unsalted butter, room temperature
1 ½cups(300 g) granulated sugar
2large eggs, room temperature
Chocolate Buttercream Frosting
1cup(226 g or 2 sticks) unsalted butter, room temperature
2cups(240 g) confectioners' sugar, sifted
1teaspoonpure vanilla extract
1-2tablespoonsmilk, room temperature
½cup(48 g) unsweetened cocoa powder
Instructions
Cupcakes
Preheat oven to 350° F. Line two standard muffin tins with paper liners and set aside.
In a medium bowl, whisk together flour, baking soda and salt. Set aside.
In a separate medium bowl, whisk together cocoa powder and espresso powder. Add the boiling water and whisk until smooth. Allow mixture to sit until room temperature, then whisk in sour cream and vanilla. Set aside.
In a the bowl of a stand mixer (or using a hand mixer), combine butter and sugar. Beat on medium-high speed until light and fluffy, about 3 minutes. Add eggs one at a time beating until combined after each addition. Scrape down the sides of the bowl as necessary.
Add one-third of the flour mixture to the large mixing bowl and mix on low speed just until combined. Add half the chocolate mixture and mix until combined. Repeat process, then end with remaining third flour mixture. Use a silicone spatula to scrape the bottoms and sides of the bowl. Mix once more for 10 seconds to ensure all ingredients are incorporated.
Transfer batter to prepared muffin tins and fill each cup two-thirds full (I like to use an ice cream scoop for this step). Bake cupcakes 18 to 22 minutes or until a tooth pick inserted in the center comes out with little to no crumbs. Allow cupcakes to cool for 5 minutes in the pan before transferring them to a wire rack to cool completely.
Frosting
In the bowl of a stand mixer, whip the butter on medium-high speed until fluffy, about 5 minutes.
With the mixer on low speed, gradually add in the confectioners' sugar and mix until completely incorporated. With the mixer on medium speed, add the vanilla and mix for 30 seconds. Add milk until desired consistency is reached.
Set aside ½ cup vanilla frosting. Put in a frosting bag with a small round tip.
Add cocoa powder to remaining frosting and mix until combined. Add milk if necessary if mixture is too thick. Transfer to a frosting bag with an open star tip.
Frost cupcakes with chocolate frosting, going in a zigzag motion across the top to make a diamond shape. Use the vanilla frosting to add stitched laces on top.
Notes
Cocoa powder: Use a good quality cocoa powder (I prefer Ghirardelli). Non-alkalized is preferred as it interacts with the baking soda to help the cupcakes rise.Espresso powder is an optional ingredient that helps strengthen the chocolate flavor. If you are sensitive to the taste, you may omit it.Sour cream may be substituted with full-fat Greek yogurt.Store cupcakes covered in an airtight container at room temperature for up to 3 days.