Preheat oven to 350 degrees F. Grease three mini bundt molds and set aside.
In a large bowl whisk cake mix and seltzer until a smooth batter forms. Fold in chopped chocolate.
Divide the batter between the bundt molds and sprinkle with black and silver sprinkles.
Bake for 12-15 minutes until cake tester comes out clean.
Let cool before removing form the cake pan. Turn out onto a cake plate.
Melt down white chocolate melting candies and drizzle liberally with white chocolate and sprinkle with more black and silver sprinkles. Let the chocolate drizzle set before serving.
Notes
I used the convection setting on my oven for this recipe. Adjust the cook time to your oven. On convection at 350 degrees F. these cakes were done in about 12-15 minutes for me.