Peel, core, and dice 1 to 2 tart apples and set aside.

In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.

In a separate bowl, whisk together the eggs, granulated sugar, light brown sugar, buttermilk, melted butter, and vanilla until smooth.

Pour the wet ingredients into the dry ingredients and stir gently until combined. Fold in the diced apples and nuts if using.

Preheat your waffle iron and grease it lightly.

Spoon about ¼ cup of batter into the waffle iron for each donut and cook until golden brown.

Transfer the cooked donuts to a wire rack to cool.

In a small bowl, whisk together the powdered sugar, milk, and vanilla to make the glaze.

Drizzle the glaze over the cooled donuts and serve warm or at room temperature.