In a large mixing bowl, whisk together the all-purpose flour, baking powder, ground cinnamon, ground nutmeg, granulated sugar, and salt until well combined.

In a separate bowl, crack in the egg and whisk it lightly. Then, add the milk, melted butter, and vanilla extract, mixing until smooth.

Carefully fold the wet ingredients into the dry mixture, stirring just until everything is combined. Gently fold in the diced apples.

Preheat your waffle iron according to the manufacturer’s instructions. Grease the plates generously with cooking spray or butter.

Once the waffle iron is preheated, spoon the batter into the center and cook for about 3–4 minutes, or until golden brown.

Whisk together the powdered sugar and milk in a medium bowl until smooth and pourable.

Once cooked, carefully remove the waffle donuts and allow them to cool slightly. Drizzle the prepared glaze over each warm donut before serving.