Preheat your oven to 350°F and position a rack in the center. Grease two 8-inch round cake pans with butter or cooking spray, then line the bottoms with parchment paper for easy removal. Combine the flour, baking powder, and salt in a medium bowl and set aside. Measure out the coconut milk, making sure to shake the can well first to distribute the cream evenly throughout—this ensures consistent coconut flavor in every slice. Have all other ingredients at room temperature, especially the butter and egg whites, as this helps create a lighter, more tender crumb.

In a large mixing bowl, beat the room-temperature butter and sugar together for about 1 minute until light and fluffy—this process incorporates air into the batter, which helps the cake rise and become tender. Reduce mixer speed and gradually add 1 1/4 cups of the coconut milk along with the coconut essence and vanilla extract, stirring until just combined. Add the dry ingredient mixture from Step 1 and mix on low speed for about 2 minutes until the flour is fully incorporated but don't overmix, as this can make the cake tough.

In a separate clean bowl, beat the 5 egg whites on high speed until stiff peaks form—this creates volume and lightness in the cake. Gently fold the whipped egg whites into the batter from Step 2 in two additions, being careful not to deflate them, as they provide the cake's tender structure. Divide the batter evenly between the prepared pans and smooth the tops. Bake at 350°F for 25 to 35 minutes until a toothpick inserted in the center comes out clean. The cakes are done when they're golden on top and spring back when lightly touched.

While the cakes bake, combine the crushed pineapple (with its juice), the 2/3 cup sugar, and cornstarch in a medium saucepan. Cook over medium heat, stirring frequently, for 5 to 8 minutes until the mixture thickens and becomes glossy and translucent—you'll notice the juice will reduce and coat the back of a spoon. This filling needs to cool completely before assembly so it won't melt the frosting. I like to spread it on a shallow plate to cool faster while I work on the frosting.

Remove the cakes from the oven and let them cool in their pans for about 10 minutes, then turn them out onto wire racks to cool completely—this prevents them from becoming too moist. Once cool, carefully cut each cake layer horizontally into two thinner layers using a serrated knife or cake leveler, working slowly and rotating the cake as you cut to ensure even layers. This creates four layers total for a more impressive, multi-layered dessert. Level off any domed tops to create flat surfaces that will stack neatly.

In a large bowl, beat together the softened butter and cream cheese for about 1 minute until smooth and creamy. Gradually add the sifted powdered sugar in batches, mixing on low speed to avoid getting powdered sugar everywhere, then increase to medium speed and beat for about 3 minutes total until light and fluffy. Pour in the 3 tablespoons of coconut milk and beat just until combined. Fold in the shredded coconut until evenly distributed. I find that sifting the powdered sugar through a fine mesh sieve prevents lumps that can create a grainy texture in the frosting.

Place the first cake layer on your serving plate or cake board and spread a thin layer of the cooled pineapple filling from Step 4 on top, then add a layer of cream cheese frosting from Step 6. Repeat with the remaining two cake layers, finishing with the top layer placed cut-side down. Spread frosting over the top and around all sides of the cake, then coat the entire outer surface with additional shredded coconut, pressing it gently so it adheres. For a neat presentation, you can reserve some frosting to pipe around the base.