Prep the apples. Finely chop the apples and divide into two, one cup for the batter and one cup for sprinkling apple bits on top of the muffins. Toss them in 1 tablespoon of lemon juice to prevent browning (optional step that I don't always do and never have browned apples).
Preheat the oven to 375°F/ 190°C. Line a muffin tray with parchment paper cups or spray with a light coating of neutral flavored spray. Set aside.
Mix the wet ingredients. In a large bowl, whisk together the dairy free milk and apple cider vinegar and let rest for 3 minutes. Then add the 1 cup of chopped apples with the oil, sugar, applesauce, vanilla extract, and a pinch of salt. Whisk until combined.
Add the dry ingredients. Into the same bowl, sift in the flour, protein powder, cinnamon, and baking powder. Switch to a spatula and mix until the batter has come together. A few lumps are okay. Scoop the prepared batter into the muffin tray. Sprinkle a few extra apples on top and sprinkle with cinnamon sugar if desired.
Bake. Bake in the prepared oven with the rack in the middle of the oven for 22-24 minutes or until a toothpick inserted into the center pulls out clean. When done, let them cool on a cooling rack for at least 15 minutes. Serve and enjoy!