Preheat your oven to 350F and grease a 9-inch round cake or pie pan.
In a medium bowl, add the apples, sugar, and cinnamon and mix to coat before setting aside.
Whisk together the sugar, cinnamon, and melted butter in a small bowl, until fully combined. Set aside.
Whisk together the flour, baking powder, and sugar in a separate large mixing bowl, until combined.
In another bowl whisk together eggs, butter (cooled), vanilla extract, and milk.
Using a spatula, add the wet ingredients to dry ingredients and mix to combine, but don’t over mix!
Fold in the apples and stir carefully and briefly. Pour the batter into the prepared cake or pie pan.
Top the batter with the cinnamon mixture and swirl it through the batter using a knife.
Bake the cake for 40-45 minutes, or until a toothpick can be inserted into the center of the cake and comes out clean. Keep note that the cinnamon swirl will still be wet when it's hot.
While the cake is baking, make the sugar glaze. Mix together the icing sugar and milk until smooth in a mixing bowl.
Pour the glaze over the warm cake and let the cake cool in the pan for 10-15 minutes.
Serve the glazed cake while still warm with a scoop of vanilla ice cream.