In a medium saucepan, simmer 2 cups of apple cider over medium heat until it reduces to about 1 cup, taking around 15-20 minutes; let it cool.

In another pan, cook diced apples with brown sugar and spices until tender, approximately 5-7 minutes. Thicken this mixture with a cornstarch slurry, cooking for another 1-2 minutes, then chill the apple filling.

Preheat your oven to 350°F (175°C) and line a standard cupcake tray with paper liners.

In a large mixing bowl, whisk together cake flour, baking powder, cinnamon, and nutmeg until well combined.

In another bowl, cream unsalted butter with light brown and granulated sugars until fluffy, about 3-4 minutes. Gradually mix in eggs and vanilla extract, followed by the reduced apple cider.

Combine the wet and dry ingredients gently until just incorporated.

Spoon the batter into the prepared cupcake liners, filling each about halfway. Bake the muffins in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool in the tray for 5 minutes, then transfer them to a wire rack to cool completely.

Once the cupcakes are cool, use a cupcake corer or a small knife to carefully remove the centers, creating space for the apple filling.

To make the brown butter cream cheese frosting, beat the cooled brown butter and room temperature cream cheese together until smooth and creamy.

Gradually add powdered sugar, cinnamon, and vanilla extract, mixing until the frosting reaches a spreadable consistency.

Frost the cooled cupcakes generously, adding a sprinkle of cinnamon or a slice of apple to garnish if desired.