In a large mixing bowl, whisk together the flour, cocoa powder, sugar, baking powder, salt, and baking soda. Make sure they're well-combined and that there are no lumps of cocoa powder.
In another bowl or a large measuring cup, beat the milk, egg, melted butter, and vanilla extract until smooth. This will be your wet mixture.
Pour the wet ingredients into the dry ingredients. Stir everything together just until combined, but don't overmix - I repeat: DO. NOT. Overmix. It's okay if there are a few small lumps – they'll cook out! If the batter is too thick, you can add a splash more milk to thin it out. Very gently fold in the chocolate chips. They'll give your pancakes delicious pockets of melted chocolate as they cook.
Heat a non-stick skillet or griddle over medium heat. Grease it lightly with butter. Once hot, pour about ¼ cup of batter for each pancake onto the skillet.
Cook the pancakes for 2-3 minutes on the first side or until you see bubbles forming on the surface and the edges look set.
Flip the pancakes carefully and cook for another 1-2 minutes on the other side, or until they are cooked through and have a nice, even color.
Transfer the cooked pancakes to a plate and cover them to keep warm. Continue with the remaining batter, adding more butter to the skillet as needed, then serve the chocolate pancakes hot with your choice of toppings. Whipped cream and berries make for a classic combo, while a drizzle of chocolate syrup can double down on the chocolatey goodness.