Preheat oven to 350 degrees. Line standard muffin tins with paper liners.

Cut the apple into cubes and put aside until use. (70% of all is for filling. The rest is for topping.)

Whisk together the flour, baking powder and baking soda and sift. Add the oats to the dry mixture and whisk together. Put aside until use.　

Cream the butter, sugar and honey. Add the eggs gradually; whisk until well mixed. Add the milk and whisk until smooth.

Add the flour mixture to the liquid mixture and use a rubber spatula to mix until half-mixed.

Add 70% of the diced apples to the mixture and stir until well mixed.

Divide the batter evenly among the lined cups. Place the rest of the diced apples on top of the muffins. Sprinkle oats over the apples.

Bake, rotating the tins halfway through. Transfer tins to wire racks to cool completely before removing the muffins.