Preheat your oven to 350°F (175°C). Grease and flour the cake pans, and line the bottoms with parchment paper for easier removal.
In a large mixing bowl, combine the flour, sugar, baking powder, and salt. Mix well.
Add the softened butter, whole milk, egg whites, vanilla extract, and melted white chocolate to the dry ingredients. Using an electric mixer, beat on medium speed until the batter is smooth and well combined, about 2-3 minutes.
Divide the batter evenly between the two prepared cake pans and smooth the tops with a rubber spatula.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Remove from the oven and let the cakes cool in the pans for 10 minutes before transferring them to a cooling rack to cool completely.
While the cakes are cooling, prepare the raspberry filling. In a saucepan, combine the raspberries, granulated sugar, cornstarch, and lemon juice. Cook over medium heat until the mixture comes to a simmer and thickens, about 5-7 minutes. Remove from heat and allow to cool.
For the frosting, beat the softened cream cheese and butter together in a mixing bowl using an electric mixer until creamy and smooth. Gradually add the powdered sugar and mix until well combined. Finally, add the melted white chocolate and vanilla extract, and mix until smooth.
Once the cakes are completely cooled, remove the tops with a serrated knife if they have domed. Place one layer of cake on a serving plate. Spread the raspberry filling evenly over the top.
Place the second cake layer on top and cover the entire cake with the white chocolate frosting using an offset spatula. Decorate with extra raspberries and shavings of white chocolate, if desired.
Slice the cake, serve, and enjoy your delicious White Chocolate Raspberry Dream Cake!