Combine the ingredients for the flax egg in a small bowl. Set aside to thicken, about 5 minutes.
In a large bowl, combine the dry ingredients and whisk together, eliminating any large clumps.
Peel and grate the apple. Then, add the shredded apple to the dry mixture. Pour in the non-dairy milk and vanilla extract. Stir until fully combined.
Over medium-low heat, add ~1/2 tsp of vegan butter or cooking spray to a nonstick skillet or griddle. Pour approximately 1/4 cup of the batter onto the pan for each pancake. When bubbles begin to rise in the pancakes and the bottom is golden, flip with a spatula and cook until golden (approximately 1-2 minutes on each side).
Serve, or place on an ovenproof plate in a 200F° oven for up to 15 minutes to keep warm.