Preheat the oven: Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan or line with parchment paper.

Make the cake batter: In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

Cream the butter and sugar: In a large bowl, cream together the softened butter and sugar until light and fluffy (about 2-3 minutes). Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

Combine with dry ingredients: Gradually add the dry ingredients to the butter mixture, alternating with sour cream. Begin and end with the dry ingredients, mixing just until combined.

Fold in raspberries and white chocolate: Gently fold in the raspberries and white chocolate chips, being careful not to break up the raspberries too much.

Bake the cake: Pour the batter into the prepared cake pan and smooth the top. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes before transferring to a wire rack to cool completely.

Make the frosting: In a small saucepan, heat the heavy cream over medium heat until it begins to simmer. Remove from the heat and add the chopped white chocolate. Stir until smooth and fully combined. Stir in the vanilla extract and let the frosting cool slightly before frosting the cake.

Frost the cake: Once the cake has cooled, spread the white chocolate frosting over the top and sides of the cake. Garnish with fresh raspberries and extra white chocolate chips if desired.

Serve: Slice and serve, enjoying the combination of moist cake, creamy frosting, and fruity bursts of raspberry.