Simmer 2 cups of apple cider in a saucepan over medium heat, reducing it by half until it thickens and becomes syrupy, about 10–15 minutes. Set aside to cool. Dice 2 apples and cook with 2 tablespoons of butter and 2 tablespoons of brown sugar in a skillet until softened, about 5–7 minutes. Thicken with a cornstarch slurry and let cool completely.

In a large bowl, whisk together 1 ½ cups of cake flour, 1 teaspoon of baking powder, 1 teaspoon of ground cinnamon, ¼ teaspoon of ground nutmeg, and ½ teaspoon of kosher salt. In a separate bowl, mix ½ cup of brown butter, ½ cup of light brown sugar, and ½ cup of granulated sugar until creamy. Add in 2 eggs and 2 teaspoons of vanilla extract, and beat well before alternating the dry mixture with the cooled apple cider until just combined.

Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners. Fill each liner halfway with the batter, about ⅓ cup each. Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean. Allow cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

Use a small knife or cupcake corer to make a hole in the center of each cupcake. Spoon the cooled apple filling into each cupcake, filling generously.

In a mixing bowl, beat together ½ cup of room-temperature cream cheese and ¼ cup of browned butter until smooth. Gradually add in 2 cups of sifted powdered sugar and 1 teaspoon of ground cinnamon, mixing to combine. Incorporate 2 tablespoons of the apple cider reduction until the frosting is light and fluffy.

Use a piping bag or spatula to generously frost each cupcake. Sprinkle with an extra dash of ground cinnamon and top with thin apple slices for an inviting touch.