Preheat oven to 325°F (165°C). Grease and flour three 9-inch cake pans.

In a small bowl, combine buttermilk and baking soda. Set aside to allow it to foam slightly.

In a large mixing bowl, cream together sugar, butter, and shortening until light and fluffy, about 3-4 minutes.

Add egg yolks one at a time, beating well after each addition.

Gradually add the flour to the creamed mixture, alternating with the buttermilk mixture, beginning and ending with flour. Mix until just combined.

Stir in vanilla extract, coconut flakes, and chopped pecans.

In a separate clean bowl, beat egg whites until stiff peaks form.

Gently fold the beaten egg whites into the batter until no white streaks remain.

Divide batter evenly among the prepared cake pans.

Bake for 25 minutes, or until a toothpick inserted in the center comes out clean.

Allow cakes to cool in pans for 10 minutes, then transfer to wire racks to cool completely.

For the frosting, beat cream cheese and butter together until smooth and creamy.

Gradually add powdered sugar and vanilla extract, beating until smooth and spreadable.

Once cake layers are completely cooled, spread frosting between layers and over the top and sides of the cake.

For an elegant finish, press additional chopped pecans around the sides of the cake if desired.