1. Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan.
2. In a medium bowl, sift together the all-purpose flour, cake flour, baking powder, and salt.
3. In a separate bowl, mix the coconut milk and vanilla extract.
4. Using a stand mixer, cream the butter and sugar on medium speed until light and fluffy, about 3-4 minutes.
5. Add egg yolks, one at a time, beating well after each addition.
6. Alternate adding the flour mixture and coconut milk mixture to the creamed butter, starting and ending with the flour. Mix until just combined.
7. In another clean bowl, beat the egg whites until they hold stiff peaks. Gently fold the egg whites into the batter, ensuring not to deflate them.
8. Fold in the shredded coconut.
9. Pour the batter into the prepared cake pan and smooth the top with a spatula.
10. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
11. Allow the cake to cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely.

Patience is key here, just like my cooking endeavors with my grandmother. Take your time folding in the egg whites to ensure that perfect cloud-like texture.