In a medium bowl, whisk flour, cocoa powder, sugar, baking powder, baking soda, and salt together. Set aside.
In a separate medium bowl, whisk buttermilk, egg, butter, and vanilla together.
Add the wet ingredients to the dry ingredients. Whisk until all ingredients are just combined. The batter should be slightly lumpy; do not overmix.
Let the batter rest as you heat the skillet or griddle.
Spray a large nonstick skillet or griddle with cooking spray. Heat over medium-low heat, about 300°F.
When hot, pour ⅓ cup of batter into the skillet. Spread the batter out to about a 4 to 5-inch diameter.
Working in batches, being careful not to overcrowd the pan, cook the pancakes for 3-4 minutes, or until the bubbles begin popping on top.
Gently, but quickly, flip over the pancakes. Cook an additional 3-4 minutes, or until cooked through and no longer doughy.
Between batches, wipe the skillet or griddle with a paper towel to prevent sticking.
Serve warm with your favorite toppings.