In a large mixing bowl, whisk together all-purpose flour, baking powder, ground cinnamon, ground nutmeg, salt, and granulated sugar until smooth.

In a separate bowl, crack the egg and whisk until frothy. Then, add milk, melted unsalted butter, and vanilla extract. Mix until combined.

Pour the wet mixture into the dry ingredients and gently fold until just combined. Avoid overmixing.

Dice the apple and gently fold it into the batter until evenly distributed.

Let the batter rest for about 5 to 10 minutes while preheating the griddle or pan.

Heat a lightly greased griddle over medium heat. Ensure it's hot enough for cooking.

Using a ladle, pour 1/4 cup of batter onto the hot griddle, spaced about 2 inches apart.

Cook the pancakes for 2 to 3 minutes until edges are set and bubbles form on the surface.

Carefully flip each pancake and cook for another 2 to 3 minutes until golden brown.

Keep cooked pancakes warm in a low oven while finishing the remaining batter.