1. Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. In a large mixing bowl, whisk together the flour, baking powder, and salt.
3. In a separate bowl, cream the softened butter and sugar until light and fluffy. Add eggs one at a time, beating well after each addition.
4. Mix in the vanilla extract and sour cream until smooth.
5. Gradually add the dry ingredients to the wet mixture, alternating with milk or heavy cream, beginning and ending with the dry ingredients.
6. Fold in the white chocolate chips or chopped white chocolate.
7. Divide the batter evenly between the prepared pans and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
8. Cool the cakes completely on wire racks.

For the frosting:
1. Beat softened butter and powdered sugar until fluffy.
2. Mix in melted white chocolate, vanilla, and a pinch of salt until smooth.
3. Frost the cooled cakes generously, smoothing to resemble the iconic white suit of Hawkeye Kingpin.