Preheat oven to 350.
Line baking sheets with parchment paper or silicone mat.
Whisk together flour, baking powder, baking soda, salt, cinnamon and nutmeg.
Stir oats into flour mixture and set aside.
Cream together butter, brown sugar and sugar.
Add in egg, apple sauce and vanilla and beat until blended.
Gradually add in the flour mixture, stirring by hand, until incorporated.
Fold in the diced apples.
Spoon into 1 tablespoon balls and place on prepared sheets 2" apart.
Bake for 18-20 minutes or until the edges are lightly browned.