Preheat the oven to 400°F and coat a baking sheet with nonstick cooking spray. In a mixing bowl, combine the flour, baking powder, cinnamon, and kosher salt, whisking to blend evenly. In a separate, larger bowl, whisk together the melted butter and granulated sugar until incorporated. Add the egg, vanilla extract, and applesauce to the mixture, stirring until smooth. Gradually mix the dry ingredients into the wet ingredients just until no dry streaks remain. Carefully fold in the diced apples.

Using a tablespoon, portion the batter and place each mound on the prepared baking sheet, spacing them several inches apart. Bake for 10 minutes, then remove the tray and switch the oven to broil on high.

While the fritters are baking, prepare the glaze by combining the powdered sugar with the apple cider or juice, whisking until the mixture is fluid and pourable. Lightly brush a portion of the glaze over the freshly baked fritter bites, allowing the glaze to drip down the sides. Broil the fritters for 2 to 4 minutes, rotating the baking sheet frequently to ensure even caramelization and bubbling of the glaze.

Take the fritters out of the oven and apply the remaining glaze generously across the tops. Let the bites rest for 15 minutes to allow the glaze to set fully before serving.