Step 1: Prepare the Cake Pans

Preheat your oven to 350°F (175°C). Grease and flour four 8-inch round cake pans to prevent sticking.

Step 2: Mix the Dry Ingredients

In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. This will ensure an even distribution of the leavening agents, resulting in a light and fluffy cake.

Step 3: Cream the Butter and Sugar

In a large mixing bowl, beat the unsalted butter and granulated sugar together on medium speed until light and fluffy, about 3-4 minutes. Gradually add the egg whites, one at a time, mixing well after each addition.

Step 4: Add the Melted White Chocolate and Vanilla

Once the egg whites are fully incorporated, stir in the melted white chocolate and vanilla extract. This step adds richness and a creamy flavor base to your cake.

Step 5: Alternate Dry Ingredients and Milk

With the mixer on low speed, alternate adding the flour mixture and milk to the butter mixture, beginning and ending with the flour. Mix just until combined to avoid overmixing, which could make the cake dense.

Step 6: Divide the Batter and Bake

Evenly divide the batter among the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Preparing the Pineapple Filling

Step 1: Cook the Pineapple Filling

In a medium saucepan, combine the chopped fresh pineapple, granulated sugar, cornstarch, lemon zest, and lemon juice. Cook over medium heat, stirring constantly, until the mixture thickens and becomes jam-like, about 10 minutes.

Step 2: Cool the Filling

Once the pineapple filling has thickened, remove it from the heat and allow it to cool completely before assembling the cake. This will prevent the filling from melting the frosting.

Making the Vanilla Buttercream Frosting

Step 1: Beat the Butter

In a large bowl, beat the butter on medium speed until creamy, about 2 minutes.

Step 2: Add the Sugar and White Chocolate

Gradually add the powdered sugar, 1/2 cup at a time, until the frosting reaches your desired sweetness. Mix in the melted white chocolate and vanilla extract.

Step 3: Adjust the Consistency

If the frosting is too thick, add heavy cream, 1 tablespoon at a time, until it reaches a smooth and spreadable consistency.

Assembling the Heavenly White Chocolate Pineapple Cake

Step 1: Layer the Cake

Place one cake layer on a serving plate or cake stand. Spread a generous amount of pineapple filling over the top, making sure it doesn’t drip over the edges.

Step 2: Repeat the Layers

Add the next cake layer on top of the filling and repeat until all layers are stacked.

Step 3: Frost the Cake

Once the layers are assembled, frost the entire cake with the vanilla buttercream. For a smoother finish, use a cake scraper or spatula.

Step 4: Decorate

For an extra touch of elegance, decorate the top of the cake with white chocolate shavings or pineapple pieces.