For the cupcakes:
Preheat the oven to 350 F (180 C).
Prepare a 12-cup muffin tin, lining it with paper cups. Set aside.
In a small bowl, whisk together the flour, baking powder, baking soda, spices, and salt.
In the bowl of a stand mixer, cream the brown sugar and butter.
Add the egg whites and beat for a few more minutes.
Alternate adding the dry ingredients and buttermilk, mixing well.
Distribute the batter among the muffin cups and bake for 20-25 minutes, or until the cupcakes are lightly browned.
Let the cupcakes rest in the pan for 5 minutes before transferring them to a wire rack to cool completely.
Mascarpone cream cheese frosting:
In a saucepan, combine the 35% cream, brown sugar, corn syrup, butter, and salt.
Bring to a boil, then reduce the heat and simmer for 15 minutes, uncovered.
Let cool completely.
Using an electric mixer, whip the mascarpone cheese while adding the cooled cream mixture.
Mix until smooth.
Refrigerate the frosting to firm it up.
Transfer the frosting to a piping bag fitted with a star tip and frost the cupcakes.
Sprinkle with colored sugar and enjoy.