In a large mixing bowl, whisk together 2 cups of all-purpose flour, ¼ cup of granulated sugar, 1 tablespoon of baking powder, ½ teaspoon of salt, and 1 teaspoon of ground cinnamon.

In a separate bowl, pour in 1 cup of milk and add 2 large eggs, ½ cup of melted butter, and 1 teaspoon of vanilla extract. Whisk these ingredients together until smooth.

Gently pour the wet mixture into the dry ingredients, and stir with a spatula until just combined.

Carefully fold in 1 cup of diced apples, ensuring they are coated with the batter.

Preheat your waffle iron and lightly grease it with cooking spray or melted butter.

Spoon about ½ cup of batter onto the preheated waffle iron and cook for approximately 4–5 minutes, until golden and crisp.

Once cooked, transfer the waffle donuts to a wire rack to cool slightly for about 5 minutes and cut out the center with a donut cutter.

In a deep pot, heat vegetable oil to 350°F (175°C) for frying.

Carefully drop the waffle donuts into the hot oil in batches, frying until golden brown for about 2–3 minutes per side.

Once golden brown, remove the waffle donuts from the oil and place them on paper towels to drain excess oil.

In a medium bowl, whisk together 1 cup of powdered sugar, 2 tablespoons of milk, and ½ teaspoon of vanilla extract until smooth.

Dip each cooled waffle donut into the glaze, allowing the excess to drip off before placing them back on the wire rack.