Preheat your oven to 350 degrees. Prepare a muffin tin with cupcake liners and set aside.
Whisk together all-purpose flour, unsweetened cocoa powder, baking powder, baking soda, and salt in a mixing bowl. Once whisked together set aside.
In a separate mixing bowl mix eggs, granulated sugar, brown sugar, vegetable oil, and vanilla extract until combined.
Slowly add in about half of your wet ingredients into your dry ingredients along with about half of your buttermilk. Mix together then add in the other half of the wet and buttermilk. Mix until just combined being careful not to overmix.
Fill each cupcake liner in your prepared cupcake pan about half way but no more then ¾. Overfull cupcakes will spill over the sides. If you need grab another cupcake pan and and cook 2-4 more extra cupcakes in that one.
Place in the oven to bake for 18-20 minutes or until cupcakes are cooked through and you could place a toothpick in the center and it would come out soon.
Allow cupcakes to cool slightly then remove them from the pan to cool completely before frosting.