Grind oats coarsely in mixer jar and transfer in a bowl. Sift all other dry ingredients i.e. wheat flour, baking powder and soda, salt and cinnamon all together in a mixing bowl. Combine everything well.
Wash and wipe the apples thoroughly. Peel both apples, chop 1 apple into fine pcs and sprinkle lemon juice, so that it doesn't turn brown.
The other one make puree in mixer grinder along with sugar. Chop walnuts roughly and keep aside.
To prepare wet mixture, take pureed apple sugar mixture, add in milk.
Fold in dry ingredients in wet ingredient to make a thick batter.
Fold in chopped apples and transfer in baking dish. Garnish with few chopped apples and chopped walnuts.
Preheat oven at 180°C. Bake in air fryer at 160 degrees for 25 min. In oven bake at 180 degrees for 25-30 minutes.
Once baked, cool down completely. Dust powdered sugar before serving.