Whisk eggs, Greek yoghurt, oat flour and baking powder until smooth and creamy.
Slice the apple thinly for even cooking and delicate texture.
Add the apple slices to the batter and fold gently.
Line a baking dish with parchment paper for easy release.
Pour the batter into the prepared dish and spread evenly.
Sprinkle sliced almonds on top if using.
Bake or air fry at 350°F / 180°C for 25–30 minutes until set.
Let the bake cool slightly to help the structure settle.
Dust with powdered sugar if desired.
Slice and enjoy warm or chilled.