Preheat your oven to 350 degrees.
Grease and flour a 9-inch springform pan lined with parchment paper
In a small bowl, combine all dry ingredients (flour, salt, and baking powder), then set it aside.
Using a stand mixer, beat the butter and sugar together until creamy and fluffy with the paddle attachment.
Add the eggs one at a time, beating after each addition. Scrape the sides of your bowl if needed
Then add the vanilla, cinnamon (if using), and rum, and beat to incorporate.
Turn off the mixer and add the flour mixture. Mix to combine with a spatula just until it's all incorporated.
Gently fold in your chopped apples.
Sprinkle the top of the batter with a bit more sugar
Pour your cake batter into your prepared cake pan
Bake for 40 minutes or until a toothpick comes out clean.
Allow the cake to cool on a cooling rack before removing it from the pan, sprinkling it with confectioners' sugar, and placing it on a serving plate for decoration.