In a large bowl, combine the all-purpose flour, granulated sugar, baking powder, baking soda, ground cinnamon, ground nutmeg, and salt. Whisk until well blended.

In a separate bowl, whisk together the buttermilk, large eggs, melted unsalted butter, and vanilla extract until fully combined.

Gently pour the wet mixture into the dry ingredients, stirring just until combined.

Carefully fold the diced apples into the batter evenly.

Cover the bowl and let the batter rest for 15-20 minutes at room temperature.

Preheat your waffle iron according to the manufacturer’s instructions and lightly grease the plates.

Pour about ½ cup of the batter onto the center of the preheated waffle iron and cook for approximately 3-5 minutes until golden brown.

Gently remove the cooked donuts and place them on a wire rack to cool.

In a medium bowl, whisk together the powdered sugar, milk, and additional vanilla until smooth.

Dip the tops of the donuts into the glaze and sprinkle with toppings before the glaze sets.

Let the glaze set for about 10-15 minutes at room temperature.

Serve warm or at room temperature.