Preheat oven to 325 degrees. Make sure oven rack is in the center position. Line a 12-cup muffin tin with cupcake liners and set aside.
In a small bowl, combine flour, baking soda, and salt. Set aside.
In a large bowl, whisk together the cocoa powder, chocolate chips, espresso powder, and boiling water until smooth and chocolate chips are completely melted.
Add in the sour cream, oil, eggs, sugar, and vanilla extract. Whisk until combined. Next, add the flour mixture and continue whisking until well combined.
Fill the muffin cups to about ⅔- ¾ full. Bake for 18-20 minutes or until a toothpick inserted comes out clean. Let cool for about 10 minutes, then transfer to a wire rack to continue cooling. Once the cupcakes are completely cooled, they are ready to be frosted.