Preheat your oven to 350°F (175°C) and line a cupcake pan with 12 cupcake liners.

In a medium bowl, sift together the cake flour, baking powder, baking soda, salt, ground nutmeg, and ground cinnamon. Set aside.

In a large mixing bowl, cream the softened unsalted butter with granulated sugar until light and fluffy for about 1-2 minutes.

Mix in the egg whites and vanilla extract until the mixture is smooth and pale.

Gradually add the dry mixture and the room temperature eggnog in alternating batches, stirring until just combined.

Divide the batter among the lined cupcake cavities, filling each about 2/3 full. Bake for 15-17 minutes.

Allow cupcakes to cool in the pan for 5 minutes before transferring them to a wire rack.

For the frosting, beat the softened unsalted butter until pale and fluffy, then gradually add the cold cream cheese.

Incorporate powdered sugar until light and creamy, then stir in ground nutmeg.

Frost the cooled cupcakes generously with the nutmeg cream cheese frosting.