Make the glaze by whisking the confectioners’ sugar with the milk or water and optional vanilla until smooth. Set it aside while preparing the fritter batter.

Whisk the flour, granulated sugar, baking powder, salt, cinnamon, and optional nutmeg together in a large bowl. This evenly distributes the leavening and spices.

In a separate bowl, whisk the milk, egg, melted butter, and vanilla extract until blended. Add the wet mixture to the dry mixture and stir just until combined.

Fold in the finely diced apples. The finished batter should be thick and scoopable rather than loose or pourable.

Heat neutral oil to 350°F (175°C) in a deep, heavy saucepan or Dutch oven. Use a thermometer so the oil remains at a reliable frying temperature.

Carefully drop portions of batter measuring about 2 tablespoons each into the oil. Fry in batches, leaving enough room for the fritters to move and cook evenly.

Cook each fritter for approximately 2–3 minutes per side, turning once, until deeply golden brown and cooked through. Adjust the heat as needed to keep the oil near 350°F.

Transfer the cooked fritters to a wire rack set over a paper-towel-lined tray, allowing excess oil to drain. Let the oil return to temperature before frying the next batch.

When the fritters are warm but no longer dripping hot, drizzle or dip them in the glaze. Serve warm for the best contrast between the crisp coating and tender apple center.