Add the flour, oatmeal, baking powder, and salt to a bowl and stir to combine. Add the butter and rub it in with your fingers. Mix the diced apple into the flour mixture.
In a second bowl, whisk together the honey, egg, and vanilla extract until the honey dissolves a bit. Pour this into the first bowl and mix until everything is incorporated. The dough will be sticky, that’s perfect.
Use two spoons or a small cookie scoop to divide the dough into 16 small mounds on a baking sheet lined with parchment paper. Gently flatten them if needed (they won’t spread much in the oven).
Bake the cookies for about 15 minutes at 190°C/375°F (conventional oven) until done and golden brown.
How to store
Keeps for 4-5 days at room temperature in an airtight container. Freezer-friendly for up to 3 months.