In a large mixing bowl, combine the cake mix, eggs, buttermilk, and vegetable oil. Use an electric mixer and beat on medium speed for about 2 minutes until smooth and well combined. Gently fold in the shredded coconut and chopped toasted pecans. These ingredients transform the boxed mix into something truly special.

Grease and flour three round cake pans. Divide the batter evenly among the pans and bake at 350°F (175°C) for 15–17 minutes, or until a toothpick inserted in the center comes out clean. Keep an eye on the cakes—overbaking can make them dry, and you want them to stay moist and tender.

Remove the pans from the oven and let them cool for about 10 minutes. Then transfer the cakes to wire racks to cool completely. This step is crucial—frosting too early can cause the frosting to melt and slide.

For an extra decadent touch, brush each cake layer with a tablespoon of rum after cooling. This not only infuses the cake with flavor but also helps keep the layers moist. Allow the cake to sit for about 10 minutes after soaking.

In a medium bowl, beat the cream cheese and butter on medium speed until smooth and creamy. Slowly add the powdered sugar while continuing to beat until the frosting becomes fluffy. Stir in vanilla extract and chopped pecans for added crunch and flavor.

Place the first cake layer on a serving platter or cake stand. Spread a generous layer of cream cheese frosting on top. Add the second layer, frost again, and repeat with the final layer. Frost the sides and top of the cake, smoothing it out with an offset spatula for a clean finish.

For best results, let the cake chill in the refrigerator for at least 2 hours before slicing. Chilling helps the frosting set and makes slicing much easier. Serve chilled and enjoy every creamy, nutty, coconut-filled bite.