Begin by preheating your waffle iron according to the manufacturer's guidelines. Lightly coat the waffle plates with cooking spray or brush with a bit of oil to prevent sticking.
In a large mixing bowl, combine the all-purpose flour, baking powder, ground cinnamon, and salt. Whisk these dry ingredients together until they are thoroughly blended and light.
In a separate mixing bowl, combine the unsweetened applesauce, granulated sugar, eggs, milk, and vanilla extract. Whisk these wet ingredients until you create a smooth and uniform mixture.
Gradually pour the wet mixture into the bowl containing the dry ingredients. Stir gently until just combined; be cautious not to overmix to ensure light and fluffy waffle donuts.
Carefully fold in the diced apples and, if desired, the chopped walnuts or pecans, making sure they are evenly distributed through the batter without overworking it.
For each waffle donut, pour approximately 1/4 to 1/3 cup of batter into the center of the preheated waffle iron. Close the lid and cook until the waffles are beautifully golden brown, typically for 4-5 minutes, or until the indicator on your waffle iron shows they are ready.
Once cooked, gently remove the waffle donuts from the waffle iron and place them on a wire rack or a plate. Repeat this process with the remaining batter until all the waffles are cooked.
To prepare the glaze, mix the powdered sugar with 2-3 tablespoons of milk in a small bowl. Stir until the mixture is smooth; you can adjust the consistency by adding more powdered sugar for thickness or more milk for a thinner glaze.
Finally, drizzle or dip the warm waffle donuts into the glaze to achieve your desired sweetness and coverage.
Notes
Serve warm with coffee or tea for a delightful treat.