Frosting:
4 ounces white chocolate finely chopped
1 1/2 cups unsalted butter at room temperature
5 1/2 to 6 1/2 cups powdered sugar
4 to 6 tablespoons whole milk or heavy cream
2 teaspoons vanilla extract
1/4 teaspoon salt
fresh raspberries for garnish

Cake layers:
Preheat the oven to 350 degrees. Spray 3 8-inch round cake pans with cooking spray and line the bottoms with parchment paper. Spray the paper with cooking spray and set pans aside.

Place the white chocolate and the butter in a microwave-safe bowl and heat on 50% powder in 15-second intervals, stirring after each interval, until chocolate is melted and mixture is smooth. Combine the remaining ingredients in a large mixing bowl and beat with an electric mixer set to medium for 2 minutes. Beat in the white chocolate until combined. Divide batter evenly between prepared cake pans and smooth with a spatula.

Bake 24 to 28 minutes, until a cake tester inserted into the center of the cake comes out clean. Cool in pans for 20 minutes, then carefully invert onto a wire rack to cool completely before filling and frosting.

Filling:
While cake is in the oven, combine all filling ingredients in a small saucepan set over medium heat. Bring to a simmer, stirring constantly, and simmer until mixture is very thick and clings to a wooden spoon. Scrape into a small bowl and refrigerate until cool enough to spread.

Frosting:
Place the chocolate in a microwave-safe bowl and heat at 50% power in 15-second intervals, stirring after each interval, until chocolate is melted and smooth. Set aside to cool for 5 minutes.

Beat the butter in a stand mixer fitted with the paddle attachment until light and creamy, about 30 seconds. Turn mixer to low and beat in 5 1/2 cups of the powdered sugar, 4 tablespoons of the milk, and the vanilla and salt until combined. Add the cooled white chocolate and mix on low until incorporated. Turn mixer to medium and mix until smooth. If frosting is too thick, add additional milk; if it’s too thin, add additional powdered sugar.

Assembly:
If your cake layers are too concave for your liking, chill the cake layers, then even them out with a long serrated knife.

Place one cake layer on a cake stand or cardboard cake circle. Make a border of icing around the edge of the layer to hold in raspberry filling. Spread half of the raspberry filling over the top of the cake (don’t go all the way to the edge). Gently spread (or pipe) a layer of frosting over the top of the filling, this time going all the way to the edge. Repeat with remaining filling and another layer of frosting. Top with remaining cake layer.

Frost your cake with remaining frosting and decorate as desired.