1. Preheat the oven to 350°F and grease a 9×13-inch baking pan or two 8-inch round cake pans. Line with parchment if needed for easier release.

2. In a medium bowl, whisk together the flour, baking powder, and salt.

3. In a large mixing bowl, beat the butter and granulated sugar until pale and fluffy.

4. Add the eggs one at a time, beating well after each addition, then mix in the vanilla extract.

5. Stir in the melted white chocolate until fully blended.

6. Add the dry ingredients in batches, alternating with the milk and sour cream, mixing just until combined.

7. Gently fold in the fresh raspberries without crushing them too much.

8. Spread the batter evenly into the prepared pan and bake for 35 to 40 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

9. Cool the cake completely before frosting.

10. To make the frosting, beat the cream cheese until smooth, then mix in the powdered sugar and melted white chocolate. Add heavy cream a little at a time until the frosting is fluffy and spreadable.

11. Spread the frosting over the cooled cake and garnish with extra raspberries and whipped cream if desired.

12. Slice and serve.