Heat oven to 350°F.
In a small bowl combine buttermilk and pumpkin. Just mix together until incorporated.
In a medium bowl, sift together flour, cocoa, baking powder, baking soda, and salt.
In a mixer, beat the butter, sugars, and vanilla together until light and fluffy.
Add in eggs, one at a time, until fully incorporated.
Alternating, add the flour mixture and buttermilk mixture to the sugar mixture, beginning and ending with the flour mixture.
Mix for 1 minute on low until fully combined.
Using an ice cream scoop or 1/4 cup measuring cup, place batter in prepared cupcake pan.
Bake for 18-22 minutes. Cupcakes are done when an inserted toothpick comes out clean.