½cup(120 g) sour cream or plain greek yogurt,, room temperature
2teaspoonspure vanilla extract
1cup(226 g or 2 sticks) unsalted butter,, room temperature
1 ½cups(300 g) granulated sugar
2large eggs,, room temperature
Chocolate Buttercream Frosting
1 ¼cups(282 g or 2 1/2 sticks) unsalted butter
2 ½cups(300 g) confectioners' sugar,, sifted
⅔cup(64 g) unsweetened cocoa powder,, sifted
1teaspoonpure vanilla extract
2-3Tablespoonsmilk
Instructions
Chocolate 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.
Chocolate Buttercream Frosting
In the bowl of a stand mixer (or using a hand mixer), beat butter on medium-high speed until light and fluffy. With the mixer on low, add sifted confectioners' sugar and cocoa powder. Mix on low until combined, then turn speed on high for 20 seconds to mix thoroughly. Add vanilla and 2 Tablespoons milk. Mix until combined and scrape down the sides of the bowl as necessary. If a thinner frosting consistency is desired, add more milk 1 teaspoon at a time.
Transfer frosting to a piping bag with desired tip (I used Wilton 1E). Pipe frosting over cooled cupcakes and serve.
Notes
Store chocolate cupcakes in an airtight container at room temperature for 3 days or in the refrigerator for 5 days.Chocolate cupcakes (unfrosted) can be individually wrapped and frozen for up to 1 month. Defrost in the refrigerator before bringing to room temperature and frosting.Half this recipe to yield only 10 cupcakes.High altitude adjustments (Denver, CO; 5,380 ft):
Use a high-protein flour such as King Arthur All Purpose Flour.
Decrease baking soda to 1/2 teaspoon.
Use 1 teaspoon freshly brewed coffee instead of espresso powder.
Decrease sugar to 1 1/4 cups.
Increase oven temperature to 365 F and bake for 18 minutes.