Preheat oven to 350 degrees F.
Line muffin pans with 16 cupcake liners.
In a medium bowl, stir together flour, cocoa powder, baking powder, baking soda and salt until well mixed. Set aside for now.
In a separate large bowl, beat together (on high) butter, brown sugar and granulated sugar until mixed well, but no longer than 2 minutes.
Beat eggs into butter mixture one at a time, beating just until mixed after each addition. Do not overmix. Stir in vanilla extract until fully combined.
Pour half the flour mixture into the wet mixture and stir (not beat) in just until combined, do not overmix. Pour all the buttermilk into the batter and stir (not beat) just until combined.
Pour in the remaining flour mixture and stir just until mixed. This is a very light and airy cupcake so if the batter is overmixed the cupcakes will sink in the middle. To prevent this, do not overmix the batter during any stage of the mixing.
Scoop batter into cupcake liners. Each liner should be about ½ filled. This will give you 16 cupcakes. If the liners are too full, the baked cupcakes will spill over and the middlescould sink in.
Place cupcakes into the oven and bake for 18 minutes or until a toothpick inserted in the middle comes out clean.
Remove cupcakes from hot muffin pan and place on wire rack to cool completely before frosting. It’s important to remove the cupcakes from the hot muffin pan as soon as they come out of the oven so they don’t continue baking and dry out.