Preheat oven to 350°F. Line the bottoms of three 8-inch round cake pans with parchment paper circles, then spray with baking spray. Set aside.
Beat butter, oil, and sugar in a large mixer on high speed for 2-3 minutes until light and fluffy.
1 cup salted butter, ¼ cup vegetable oil, 1¾ cups granulated sugar
Add eggs, egg whites, vanilla extract, and coconut extract. Beat well for 2 minutes, stopping to scrape the bottom and sides of bowl partway through.
2 large eggs, 4 egg whites, 1 teaspoon vanilla extract, 1 teaspoon coconut extract
Whisk cake flour, baking powder, and salt in another bowl to combine.
3 cups cake flour, 1 Tablespoon baking powder, ½ teaspoon salt
Add flour mixture in two additions alternately with coconut milk, mixing between each addition. Stir in the coconut.
1 cup coconut milk, 1 cup shredded sweetened coconut
Evenly divide batter between the prepared pans. Bake for 20-25 minutes until done. Dry crumbs should cling to a toothpick when inserted into center of each cake.
Cool completely on a wire rack before filling and frosting.