1. In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, ground cinnamon, and granulated sugar.

2. In a separate bowl, whisk together the milk, egg, vanilla extract, and melted unsalted butter.

3. Pour the wet ingredients into the dry ingredients and stir until just combined, being careful not to overmix.

4. Gently fold in the diced apples, ensuring they are evenly distributed throughout the batter.

5. Preheat a griddle or large skillet over medium heat and lightly grease with butter or cooking spray.

6. Scoop 1/4 cup of the batter onto the hot surface for each pancake. Cook until bubbles begin to form on the surface and the edges look set, about 2-3 minutes.

7. Flip the pancakes and cook for an additional 2-3 minutes, or until golden brown and cooked through. Remove the pancakes from the griddle and keep them warm while you continue cooking the remaining batter.

8. In a small bowl, whisk together the powdered sugar, milk, vanilla extract, and ground cinnamon (if using) until the mixture is smooth and pourable.

9. Drizzle the warm glaze over the freshly cooked Apple Fritter Pancakes and serve immediately.