Preheat oven to 350°F (175°C). Grease and flour three 9-inch round cake pans.

Melt the chopped white chocolate in a microwave-safe bowl in 20-second increments, stirring until smooth. Set aside to cool slightly.

In a medium bowl, whisk together flour, baking soda, and salt.

In a large bowl, beat butter and sugar with an electric mixer until light and fluffy. Add egg yolks, one at a time, beating well after each addition. Mix in the melted white chocolate and vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with buttermilk, beginning and ending with flour. Mix until just combined.

In a separate bowl, beat egg whites until stiff peaks form. Gently fold them into the batter.

Divide the batter evenly among the three prepared pans. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.

Cool cakes in pans for 10 minutes, then transfer to wire racks to cool completely.

Make the Frosting:

In a large saucepan, combine evaporated milk, both sugars, butter, and egg yolks. Cook over medium heat, whisking constantly, until mixture thickens and coats the back of a spoon (about 12 minutes).

Remove from heat and stir in pecans, shredded coconut, and vanilla. Let frosting cool until spreadable.

Assemble the Cake:

Place one cake layer on a serving plate and spread frosting evenly on top.

Repeat with the second and third layers.

Spread remaining frosting on top and sides of the cake.

Let set before slicing and serving.