Preheat oven to 400°F (200°C). Lightly grease a baking sheet with nonstick spray and line with parchment.
In a medium bowl, whisk together flour, baking powder, salt, and cinnamon.
In another bowl, combine melted butter and sugar. Whisk in the egg, then add vanilla and applesauce.
Gradually fold dry ingredients into wet just until combined. Do not overmix.
Gently stir in the diced apples.
Drop 1-tablespoon portions of batter onto the prepared sheet, spacing about 1 inch (2.5 cm) apart.
Bake for 10 minutes, until set and lightly golden.
While baking, whisk powdered sugar with apple cider until smooth and pourable.
Switch oven to broil. Brush each fritter with glaze; broil 2–4 minutes until the glaze bubbles and lightly caramelizes. Watch closely.
Brush with a second coat of glaze and let sit 15 minutes to set. Serve warm.