Ingredients:

For the White Chocolate Cake:

• 2 1/2 cups all-purpose flour
• 2 teaspoons baking powder
• 1/2 teaspoon salt
• 3/4 cup unsalted butter, room temperature
• 1 1/2 cups granulated sugar
• 4 large egg whites, room temperature
• 100g white chocolate, melted and cooled
• 1 cup whole milk, room temperature
• 1 teaspoon pure vanilla extract

For the Pineapple Filling:

• 2 cups chopped fresh pineapple
• 1/2 cup granulated sugar
• 2 tablespoons cornstarch
• 1/2 teaspoon lemon zest
• 1 tablespoon lemon juice

For the Vanilla Buttercream Frosting:

• 1 1/2 cups unsalted butter, room temperature
• 4-5 cups powdered sugar, sifted
• 200g white chocolate, melted and cooled
• 2 teaspoons pure vanilla extract
• 2-3 tablespoons heavy cream (adjust for desired consistency)

Instructions:

1. Preheat your oven to 350°F (175°C).
2. Grease and flour three 8-inch round cake pans.
3. Whisk together the flour, baking powder, and salt.
4. Set aside.
5. Beat the butter and sugar until light and fluffy.
6. Gradually add egg whites, mixing well.
7. Stir in melted white chocolate and vanilla extract.
8. Alternate adding the flour mixture and milk to the butter mixture, starting and ending with flour.
9. Divide the batter evenly among the pans and bake for 25-30 minutes.
10. Cool for 10 minutes, then turn out onto a wire rack.
11. For the filling, combine pineapple, sugar, cornstarch, lemon zest, and lemon juice in a saucepan over medium heat.
12. Cook until thickened.
13. Cool completely.
14. For the frosting, beat butter until creamy.
15. Gradually add powdered sugar and melted white chocolate.
16. Mix in vanilla and heavy cream until smooth.
17. To assemble, place one cake layer on a plate, spread with pineapple filling, then add the next layer and repeat.
18. Frost the entire cake with the vanilla buttercream.
19. Decorate with white chocolate shavings or pieces of pineapple if desired.