In a microwave-safe bowl, heat diced apples and water for ~2 minutes until soft. Drain water, but reserve to thin batter if needed. Set apples aside.
Heat a griddle or large non-stick pan over medium-low heat. While griddle is heating, in a large bowl, gently whisk flour, cinnamon, baking powder, baking soda, and salt.
In a separate medium bowl, whisk buttermilk, butter, brown sugar, egg, and vanilla. If it looks too thick, add a little more buttermilk (buttermilk thickness can vary) or the reserved water from the apples. Add liquid ingredients to the flour mixture. Using a spatula, stir to combine. Gently fold in diced apples. Do not overmix.
Lightly grease griddle or pan with non-stick spray or a little butter. Pour ~¼ cup batter onto griddle to create pancakes. Cook until tiny bubbles appear on the surface and edges start to firm up.
Flip and cook ~2 more minutes. You might need to lower the heat as you cook additional batches. Hold in the oven on a warming setting or about 170° F until ready to eat. Enjoy!