In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt. In a medium bowl, whisk together the milk, eggs, melted butter, and vanilla extract until well combined.

Pour the wet mixture into the dry mixture and stir together until almost combined. Add the chocolate chips and stir a few times until evenly distributed. (A few lumps in the batter are okay and actually result in fluffier pancakes, so don’t try to stir it until smooth.)

Heat a large non-stick skillet over medium heat. Lightly grease with butter. Working in batches, drop the pancake batter into the hot skillet using about ¼ cup per pancake. Sprinkle the top of each pancake with more chocolate chips, if desired. Cook until the edges are set and lots of bubbles have formed on top of each pancake, about 3 minutes.

Carefully flip and continue cooking until golden brown, and the centers feel springy when you press on them, 1 to 2 minutes. Transfer to a plate and keep warm while you cook the rest of the pancakes. Serve hot with butter and maple syrup.