- Mix flour, oat flakes (you can grind a little with a grinder) and baking powder.
- Beat the egg with sugar, pour in the melted cold butter, and beat again.
- Cut the apple into cubes and add to the dough, then mix quickly.
- Leave in the fridge for an hour.
- Wet your hands. Form balls the size of a walnut, then put on a baking sheet covered with parchment, and flatten with your palm.
- Bake the cookies in the oven preheated to 392F (200C) for 15-17 minutes. The main thing is not to overdo!
- Cool the cookies.
- Put 2 large marshmallows on half of the cookies. Put these cookies in the microwave for 1 minute, and then cover with remaining cookies on top.
- Dip in dark/milk chocolate. Decorate with white chocolate or sprinkle with nuts on top.
- Some of the cookies can be left just like that, and some can be turned into cookie sandwiches.