Combine flour, sugar, baking powder, baking soda, salt, cinnamon, and allspice in a medium bowl, whisking them together thoroughly. Set the mixture aside.
In a separate large glass measuring cup or small bowl, whisk together the buttermilk, canola oil, egg, and vanilla extract until well blended.
Pour the wet ingredients over the dry ingredients in the medium bowl. Whisk the mixture until just combined, being careful not to overmix. Gently fold in the diced apples.
Heat a griddle pan or non-stick skillet over medium heat. Add a tablespoon of butter and let it melt across the pan. Pour approximately 1/4 cup of pancake batter at a time onto the hot griddle pan, making sure to space out the pancakes a few inches apart. Once the pancakes begin to bubble up, flip them and cook until lightly browned.
While the pancakes are cooking, prepare the cinnamon syrup. In a small saucepan, stir together the dry ingredients, then add water and vanilla extract. Bring the mixture to a rolling boil, stirring often. Allow it to continue boiling and stirring until it thickens to a syrup consistency, which should take about 5-8 minutes. Remove the syrup from the heat and let it stand for a few minutes before serving.
Serve the apple cinnamon pancakes with the prepared cinnamon syrup and enjoy your delicious breakfast!