Preheat oven to 350 degrees F (175 degrees C). Grease and flour a muffin tin.
In a large bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt.
In a separate bowl, cream together the butter and sugar until light and fluffy. Beat in eggs, one at a time, then stir in the vanilla.
Stir the grated carrots, raisins, walnuts, and white chocolate chips into the creamed mixture.
Stir the dry ingredients into the wet ingredients until just blended.
Fill the muffin tin cups 2/3 full. Bake for 20 to 25 minutes in the preheated oven, or until a toothpick inserted into the center of a cupcake comes out clean.
To make the icing: Beat together the butter, cream cheese, and vanilla extract until smooth. Gradually beat in the confectioners sugar until light and fluffy. Beat in the melted white chocolate chips until fully incorporated.
Frost the cooled cupcakes with the icing.
Interesting Facts
Carrots are an excellent source of vitamin A, which is essential for healthy vision.
White chocolate is lower in cocoa content than dark or milk chocolate, making it sweeter.
Cream cheese icing is a popular choice for carrot cupcakes because it is light and fluffy and complements the natural sweetness of the carrots.