Preheat the oven to 350°F (175°C) and grease two 8-inch round cake pans.
In a large mixing bowl, combine the cake mix, pineapple with juice, shredded coconut, softened butter, granulated sugar, milk, and eggs. Mix until the batter is smooth and well-blended.
Divide the batter evenly between the prepared cake pans.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool completely before frosting.
To prepare the frosting, whip the heavy cream and powdered sugar in a large bowl until stiff peaks form.
Fold in the shredded coconut and drained pineapple gently.
Frost the first layer of the cake, then place the second layer on top and frost the entire cake.
Decorate with additional coconut flakes and pineapple chunks, if desired.
Chill for 30 minutes before serving to allow the flavors to meld.