Preheat the oven to 350°F. Line 24 muffin tins with cupcake papers and set aside.
In a large bowl, combine flour, cocoa powder, baking powder, baking soda, cinnamon, nutmeg, and salt; set aside. In a medium bowl or large liquid measuring cup, combine buttermilk, pumpkin, and vanilla, and whisk until smooth. In a large bowl or the bowl of a stand mixer, beat butter and sugars until light and fluffy. Add eggs and beat until incorporated. Add ⅓ of the flour mixture, and beat until combined. Add ½ of the buttermilk mixture, and beat until combined. Repeat until all ingredients have been added and batter is well-mixed.
Divide batter evenly among prepared pans. Bake 18-22 minutes, until a toothpick inserted in the center of a cupcake comes out clean.
Allow cupcakes to cool completely before frosting.
Recipe by Lulu the Baker at https://luluthebaker.com/chocolate-pumpkin-spice-cupcakes/