If using vinegar substitute, combine whole milk and vinegar, set aside.
In a large mixing bowl, sift together all-purpose flour, granulated sugar, baking powder, and salt.
In another bowl, mix melted butter, vanilla extract, and the large egg.
Combine the wet and dry ingredients, being careful not to overmix; leave the batter slightly lumpy for fluffier pancakes.
Heat a nonstick frying pan over medium heat, spray with non-stick cooking spray.
Pour half a cup of batter into the pan and cook until golden on the bottom with bubbles appearing on top.
Flip and cook for an additional minute or until golden brown.
Cook pancakes in batches, adding more cooking spray as needed.
Thin Pancake Variation:
For picky eaters who prefer thin pancakes, overmix the batter to develop gluten, resulting in thinner and flatter pancakes. Cook them similarly to the fluffy ones until golden brown.