Preheat oven to 350F, and place a rack in the middle of the oven.
Peel, core, and dice the apples into small cubes, about ¼ inch. You should have about 1-1½ cup. Toss in the cinnamon and 2 tsp of sugar. Set aside for later.
For the dry ingredients, in a medium/large bowl, combine the flour, baking powder, and salt with a whisk.
For the wet, in a medium bowl, combine the 1 cup of sugar, oil, oat milk, and vanilla paste/extract with a whisk.
Pour the wet into the dry, and fold with a rubber spatula until smooth, making sure not to over-mix.
Now line the muffin tins with muffin papers, and fill them up about ¼ inch shy of the top, should be around ¼-⅓ cup of batter per muffin.
Spoon about 2 tsp - 1 TBS of the apple cinnamon mixture over the top of all the muffins, then press them down with a spoon or the palm of your hand. Sprinkle the tops with sugar.
Now bake the muffins on the middle rack of the oven for 30-35 minutes. Once done, allow them to cool for no less than 10 minutes before eating.
Enjoy!