In a large mixing bowl, whisk together the dry ingredients: all-purpose flour, baking powder, ground cinnamon, ground nutmeg, and granulated sugar until evenly incorporated.

In a separate bowl, whisk together the wet ingredients: beaten eggs, milk, melted butter, and vanilla extract until smooth and homogenous.

Gently fold the wet ingredients into the dry mixture using a rubber spatula. Stir just until combined; a few lumps should remain.

Carefully fold in the diced apples, ensuring an even distribution throughout the batter.

Preheat your waffle iron according to the manufacturer's instructions and grease both the top and bottom plates.

Spoon about 1/2 cup of batter into the center of the preheated waffle iron, close the lid, and cook for approximately 3-4 minutes.

In a small bowl, whisk together powdered sugar, milk, and a splash of vanilla extract until smooth and reached drizzling consistency.

Once the waffle donuts are cooked, drizzle the prepared glaze generously on top before serving warm.