Preheat and prep: Set the oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone mat.

Mix dry ingredients: In a large bowl, stir together oats, whole wheat flour, baking powder, cinnamon, and salt. Break up any flour clumps so the mix is even.

Make the wet mixture: In a separate bowl, whisk the applesauce, maple syrup, egg, melted butter, and vanilla until smooth. If using a flax egg, mix it first and let it sit for 5 minutes before adding.

Combine: Pour the wet mixture into the dry. Stir gently until almost combined. Fold in the grated apple and any optional add-ins. The dough will be thick and sticky.

Rest the dough: Let the mixture sit for 5–10 minutes. This hydrates the oats and makes the cookies bake up tender instead of crumbly.

Scoop and flatten: Use a tablespoon or small cookie scoop to portion dough onto the baking sheet, leaving about 2 inches between cookies. Moisten your fingers and gently press each mound into a thick disk, about 1/2 inch thick.

Bake: Bake for 10–13 minutes, until the edges are set and the bottoms are lightly golden. The centers should feel soft but not wet.

Cool: Let cookies sit on the sheet for 5 minutes to firm up, then transfer to a wire rack. They’ll continue to set as they cool.

Serve: Enjoy warm or at room temperature. For younger kids, you can break cookies into bite-size pieces for easy snacking.