Mix Dry Ingredients:
In a large bowl, whisk together the flour, granulated sugar, baking powder, and salt.

Combine Wet Ingredients:
In a separate bowl, beat the egg lightly and mix in the milk, melted butter, and vanilla extract until well combined.

Form the Batter:
Gradually add the wet ingredients into the dry ingredients. Stir gently until just combined (lumps are okay to keep the pancakes fluffy).

Prepare the Cinnamon Swirl:
In a small bowl, combine the ground cinnamon, brown sugar, and melted butter until a smooth paste forms.

Create the Swirl:
Heat a non-stick skillet or griddle over medium heat. Pour a small ladle of batter onto the surface. Drop a teaspoon of the cinnamon mixture in the center and use a toothpick or the back of a spoon to gently swirl the cinnamon paste into the batter. Repeat with remaining batter.

Cook the Pancakes:
Cook each pancake for about 2-3 minutes until bubbles form on the surface and edges look set. Flip carefully and cook for an additional 2 minutes until golden brown and fully cooked.

Serve:
Serve the pancakes warm with your favorite toppings, such as maple syrup, a dusting of powdered sugar, or a dollop of whipped cream.