In a large bowl, combine the flour, sugar, baking powder, baking soda, cinnamon and salt. In a separate bowl whisk together the buttermilk, butter, eggs and vanilla. Add liquids to the flour mixture and mix until just combined. Add the chopped apples and mix only until incorporated.
Preheat a waffle iron and cook waffles according to manufacturer's instructions. Let cool and cut into segments.
Pour enough vegetable or canola oil into a heavy bottomed pot so that it's 2 inches deep. Set over medium heat, insert a thermometer, and heat to 360° F.
Working with the waffles in small batches, fry until golden brown, about 2 minutes on each side. Use a slotted spoon to remove doughnuts and transfer to a paper towel lined tray to drain.
To make the glaze, whisk together the powdered sugar, milk and vanilla extract. Dip the hot doughnuts into the glaze and let sit on a wire rack for 20 minutes before serving.
Calories: 191kcal, Carbohydrates: 36g, Protein: 3g, Fat: 4g, Saturated Fat: 2g, Cholesterol: 30mg, Sodium: 203mg, Potassium: 112mg, Fiber: 1g, Sugar: 23g, Vitamin A: 152IU, Vitamin C: 1mg, Calcium: 49mg, Iron: 1mg