Preheat the oven to 350°F (175°C) and grease and flour two 9-inch round cake pans.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy.

Carefully add the egg whites, one at a time, ensuring each is fully combined before adding the next.

Gradually add the milk and vanilla extract to the butter mixture, mixing to combine.

Slowly add the dry ingredients to the wet mixture, mixing until just combined.

Fold in the melted white chocolate gently until evenly mixed.

Pour the batter evenly into the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Remove the cakes from the oven and let them cool in the pans for about 10 minutes before transferring to a wire rack to cool completely.

While the cakes cool, mix the shredded coconut and chopped pecans (if using) in a bowl.

Once cooled, place one layer of cake on a serving plate, spread the topping generously, and then gently place the second cake layer on top. Finish with the remaining topping.