In a medium sized bowl, combine the soy milk and lemon juice and allow to sit for 5 minutes. This creates vegan buttermilk and will make for moist and fluffy pancakes.
While your vegan buttermilk is "curdling," combine the buckwheat flour, white flour, salt, baking soda, ½ tsp cinnamon, and nutmeg in a large bowl. Whisk until completely mixed.
Add the apple sauce and melted vegan butter to the vegan buttermilk and stir to combine thoroughly.
Add the wet buttermilk mixture into the large bowl with the dry flour mixture and mix with a wooden smooth until just combined. Do not overmix. Allow the batter to rest for 5 minutes before cooking.
While the batter is resting, slice the apple into thin and even ⅛" slices using a knife or mandoline slicer. Add to a small bowl and sprinkle the remaining cinnamon onto the apples, stirring to distribute evenly.
Heat a skillet on medium high heat and add the olive oil, spreading it to cover the skillet thoroughly. You can test the temperature of the skillet by dropping a small dollop of the batter onto the pan. If it starts sizzling immediately, the skillet is hot enough.
Grease the mason jar ring then drop bottom down onto the pan using a pair of tongs. Lay 3 apple slices inside the ring. Pour ¼ cup of batter into the ring on top of the apples then remove the ring immediately using the tongs. Repeat as needed to fill up the skillet.
When the pancakes begin to bubble on the inside and the edges are golden brown, flip them using a spatula and continue to cook 1-2 minutes on the other side.
Remove the pancakes, cover with your favorite toppings, and enjoy!