Preheat oven to 180C or 350F. Get ready four 9-in. round baking pans. Line the baking pan with parchment paper. If you don't have parchment paper, grease, and flour the pans. Weigh the bowl that will be used to prepare the cake batter. It would help to distribute the batter into the pans equally.

Make sure that butter and white baking chocolate are at room temperature. If you are using the white chocolate bar, chop them into small pieces. Powder the sugar.

Prepare white chocolate cake - Start with the four 9 inch cakes which will make the four layers of the cake. Combine butter, chocolate, sugar, and milk in medium saucepan. To be safe, you can use a double boiler. Mix it well and stir over low heat, without boiling, until smooth. Let it cool down. It might take around 15 to 20 minutes. Use Ice-water bath and frequently stirring for faster and more even cooling. Transfer mixture to a large bowl.

Mix flour and baking powder in another bowl. Whisk it in the above mixture. Add essence and eggs. Whisk it until batter is smooth. Pour the batter equally into the 4 prepared pans, bake for about 25 minutes to 30 minutes or until a toothpick inserted in the center comes out clean. Let the cakes cool down completely.

Meanwhile, prepare the fillings. For the raspberry filling, in a small saucepan, add the fresh raspberry. Add sugar, lemon juice, and cornstarch into the pan. Mix it well. Cook over medium heat and mash few raspberries. Stir it continuously until the mixture thickens. Add extra sugar if needed. I didn't make it too sweet. Remove from the heat. Allow it to cool. This raspberry filling can be refrigerated in a covered container for a week.

Prepare white chocolate and cream cheese filling - Refer notes on how to melt white baking chocolate. In a large bowl, beat cream cheese and butter until fluffy. Beat in cooled melted chocolate and vanilla essence. Gradually add confectioners' sugar until smooth. I would say, taste and add sugar up to the sweetness you need. I don't like to make this filling too sweet. I love to retain the tanginess of the cream cheese. Refer notes on further details of the filling.

Prepare white chocolate ganache frosting - Melt the white baking chocolate for 30s in microwave so that it gets mixed with the cream easily. Refer notes on how to melt chocolate. Bring cream to a boil in a small saucepan. Pour over chocolate and stir with a spoon until chocolate melts completely. Cream and chocolate should get mixed well. Let it cool down. Using a stand mixer with whisk attachment or using a hand mixer, beat melted chocolate ganache on high until light and fluffy. If you want to add color, add it at this moment. I added light pink color to this frosting.

Prepare thin white chocolate ganache - Thin white chocolate ganache is optional. As in the picture, the lavender top is the thin, pourable ganache. Follow the same steps as white chocolate ganache frosting to prepare pourable ganache but follow the measurements as listed in the ingredients section. I added lavender color to this.

Assemble the cake - Remove the cakes from the pan. Place one cake layer on the cake board. Spread with one-third white chocolate cream cheese filling. Add one-third raspberry filling on top of it. Spread it. Repeat layers. Top with remaining cake layer.

Spread white chocolate ganache over top and sides of cake. In my case, it's the pink frosting. Pour the thin white chocolate lavender ganache on the top.