Preheat your oven to 375°F (190°C) and prepare a baking sheet by lining it with parchment paper to prevent sticking.
In a large mixing bowl, whisk together the all-purpose flour, baking powder, ground cinnamon, salt, granulated sugar, and packed brown sugar until everything is evenly blended.
In another bowl, beat the egg until it's frothy. Then, add the milk and vanilla extract to the egg, mixing until well combined.
Pour the wet mixture into the bowl with the dry ingredients. Stir gently with a spatula or wooden spoon until just combined; be cautious not to overmix as this could make the fritters dense.
Carefully fold in the finely chopped apples and optional raisins, ensuring they are distributed evenly throughout the batter.
Using a spoon or an ice cream scoop, drop generous dollops of the batter onto the prepared baking sheet, ensuring to space them a few inches apart for even baking.
Bake in the preheated oven for about 15-20 minutes, or until the fritters are lightly golden on top and a toothpick inserted into the center comes out clean.
While the fritters are baking, prepare the glaze by combining the powdered sugar and 2 tablespoons of milk in a small bowl. Whisk until smooth; adjust the thickness by adding more powdered sugar or milk to your preference.
Once the fritters are finished, remove them from the oven and allow them to cool for a few minutes on the baking sheet before transferring them to a wire rack.
Drizzle the glaze generously over the warm fritters just before serving to allow it to seep into the warm dough.
Notes
Serve warm with a dusting of powdered sugar and optional apple slices.