1️⃣ Preheat the Oven:
Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan with butter or nonstick cooking spray, and line it with parchment paper if desired.

2️⃣ Mix the Dry Ingredients:
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.

3️⃣ Cream the Butter and Sugar:
In a large mixing bowl, cream the softened butter and granulated sugar using a hand or stand mixer until light and fluffy.

4️⃣ Incorporate the Egg Yolks and Vanilla:
Add the egg yolks one at a time, beating well after each addition. Mix in the vanilla extract.

5️⃣ Combine Wet and Dry Ingredients:
Gradually add the dry ingredients to the creamed mixture, alternating with the buttermilk. Begin and end with the dry ingredients. Mix until just combined. Fold in the shredded coconut and chopped pecans or walnuts.

6️⃣ Whip the Egg Whites:
In a separate clean mixing bowl, beat the egg whites until stiff peaks form. Gently fold the beaten egg whites into the batter, being careful not to deflate the mixture.

7️⃣ Bake the Cake:
Pour the batter into the prepared baking pan, spreading it evenly. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Remove from the oven and allow the cake to cool completely in the pan on a wire rack.

8️⃣ Prepare the Cream Cheese Frosting:
Beat the softened butter and cream cheese in a mixing bowl until smooth and creamy. Gradually add the powdered sugar, one cup at a time, beating well after each addition. Stir in the vanilla extract until fully incorporated.

9️⃣ Frost the Cake:
Once the cake is completely cool, spread the cream cheese frosting evenly over the top. For garnish, sprinkle additional shredded coconut and chopped pecans or walnuts on top if desired.

🔟 Serve and Enjoy:
Slice the Italian Cream Sheet Cake into squares and serve. Refrigerate any leftovers in an airtight container for up to 5 days.