Preheat oven to 350°F. Grease and flour a 10-12 cup bundt pan or spray well with baking spray.
In a large bowl, beat the butter and sugar until creamy and light, about 2-3 minutes. Add eggs, one at a time, stopping to scrape the bottom and sides of the bowl.
¾ cup salted butter, 1½ cups (300g) granulated sugar, 3 large eggs
Add the sour cream and vanilla extract, stirring well until combined.
1¼ cups sour cream, 1 teaspoon pure vanilla extract
Add the flour along with the baking powder, baking soda, and salt. Mix on low speed just until mostly incorporated. Stop to scrape the bottom and sides of the bowl until you have a thick batter.
2½ cups (353g) all-purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon salt
Stir in the chopped white chocolate by hand until evenly dispersed.
1¼ cups roughly chopped white chocolate
Add ⅓ of the batter to the pan and smooth out. Drop spoonfuls of about half of the raspberry filling over the batter and lightly swirl in. Add another ⅓ of the batter and repeat with the remaining raspberry filling, trying to avoid getting the raspberry filling against the sides of the pan as much as possible to prevent the cake from sticking. Top with the remaining batter and gently swirl.
⅔ cup raspberry pie filling
Bake 50 to 60 minutes or until a skewer inserted into the thickest part of the cake comes out clean with just a few crumbs. Let cool for 10 minutes before turning the cake out onto a cake plate or wire rack to finish cooling before frosting.
To make the frosting, beat the cream cheese and butter in a large mixing bowl until smooth and combined. Add the melted white chocolate, mixing just until combined. Add the powdered sugar and vanilla extract, then continue to mix until smooth and combined. Do not overmix the frosting.
3 ounces white chocolate, 1 (8-ounce) package cream cheese, ¼ cup salted butter, 3-4 cups powdered sugar, 2 teaspoons vanilla extract
Transfer the frosting to a piping bag with a round tip or a large gallon-size ziploc bag with one corner snipped off. Pipe thick ribbons of frosting from the inside of the cake to the outside to finish.