Preheat oven to 325 degrees.
In a large bowl, combine the cake mix, pudding mix, sour cream, eggs, milk and oil.
Chop up the white chocolate and add it to the cake batter.
Coat a bundt pan generously with nonstick cooking spray. Pour 1/3 of the batter into the pan. Dot 1/4 cup of the raspberry preserves onto the cake batter. Use a knife to swirl it around.
Repeat this process two more times with the cake batter and preserves.
Bake 65 minutes, or until a toothpick inserted into the center of the cake comes out clean.
To make the frosting, beat the cream cheese, butter, confectioner's sugar and vanilla together in the bowl of a stand mixer. Alternatively, use a handheld electric mixer.
Invert the completely cooled cake onto a serving plate.
Fill a piping bag with the frosting and snip off the tip of the bag. Pipe frosting along the lines created by the bundt pan. Garnish the top of the cake with fresh berries and additional white chocolate, if desired.