Dice the apple and put it in a microwave-safe bowl.
Add cinnamon, vanilla, and a tiny pinch of salt.
Microwave 1½–2 minutes, until softened.
Mix oats, brown sugar/maple syrup, and light butter together until crumbly.
Sprinkle over the apple.
Microwave another 30–45 seconds or bake/air fry at 375°F for 8–10 minutes.