01 - Preheat oven to 350°F. Grease and line three 8-inch round cake pans with parchment paper.
02 - Whisk together flour, baking powder, and salt in a medium bowl until well combined.
03 - Beat butter and sugar in a large bowl until light and fluffy, approximately 3 minutes. Add eggs one at a time, beating thoroughly after each addition.
04 - Fold in melted cooled white chocolate and vanilla extract until just incorporated.
05 - Add flour mixture to wet ingredients in three alternating parts with milk, beginning and ending with flour. Mix until just combined, being careful not to overmix.
06 - Divide batter evenly among prepared pans. Bake for 22 to 26 minutes until a toothpick inserted comes out clean. Cool in pans for 10 minutes, then transfer to wire racks to cool completely.
07 - Combine sugar, evaporated milk, egg yolks, and butter in a medium saucepan over medium heat. Cook while stirring constantly until mixture thickens and turns golden, about 10 to 12 minutes.
08 - Remove from heat. Stir in coconut, pecans, vanilla, and salt. Allow to cool to room temperature before using.
09 - Place one cake layer on a serving plate. Spread with one-third of the coconut-pecan filling. Repeat with remaining layers and filling. Garnish with chopped white chocolate, coconut, or pecans if desired.
10 - Refrigerate cake for 1 hour before slicing to ensure clean cuts.