Start by preheating your oven to 350°F (175°C). Prepare a 9x13-inch baking pan by greasing it and lining it with parchment paper for easy removal. You can also lightly coat it with non-stick spray.

In a medium bowl, whisk together flour, baking soda, and salt. In a separate large mixing bowl, cream the butter and granulated sugar until light and fluffy. Add the egg yolks one at a time, beating well after each addition. Mix in the vanilla extract.

Gradually add the dry flour mixture to the butter mixture, alternating with the buttermilk. Stir until just combined, ensuring not to overmix. Fold in shredded coconut and chopped pecans or walnuts.

In another clean mixing bowl, beat the egg whites until stiff peaks form. Gently fold these whipped whites into the cake batter. This step helps keep the cake airy and moist.

Spread the batter evenly into the prepared baking pan. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Remove the cake from the oven and allow it to cool completely in the pan.

In a mixing bowl, beat together softened butter and cream cheese until smooth and creamy. Gradually add powdered sugar, one cup at a time, and mix until fully incorporated. Stir in vanilla extract. The frosting should be thick but spreadable.

Once the cake has completely cooled, spread the cream cheese frosting evenly over the top. Garnish with extra shredded coconut and chopped pecans or walnuts for added flavor and visual appeal.

Cut into squares or rectangles and serve. Store leftovers in an airtight container in the refrigerator for up to 5 days.