In a small pot, combine diced apples, brown sugar, cornstarch, and cinnamon with a splash of water. Bring to a boil, then cover and reduce heat to simmer for about 10-15 minutes.

Preheat your oven to 350°F (175°C) and line cupcake pan with liners.

In a bowl, whisk together cake flour, baking powder, ground cinnamon, and salt.

In a large bowl, beat softened unsalted butter until creamy. Gradually add sugar and beat until light and fluffy.

Add in room-temperature eggs one at a time, blending well after each, then blend in vanilla extract.

Gently add the dry ingredients alternately with the milk to the wet mixture, mixing until just combined.

Spoon batter into cupcake liners, filling two-thirds full, and bake for 18-20 minutes until toothpick comes out clean.

While cooling, prepare frosting by beating cream cheese and butter until smooth, then gradually add powdered sugar and cinnamon.

Scoop out a small portion from the center of each cooled cupcake, fill with apple filling, and frost generously on top.