1️⃣ Preheat the oven:
Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking pan and line it with parchment paper, or coat it lightly with non-stick cooking spray.

2️⃣ Mix dry ingredients:
In a medium bowl, whisk together the flour, baking soda, and salt.

3️⃣ Cream butter and sugar:
In a large mixing bowl, use a hand or stand mixer to cream together the softened butter and granulated sugar until light and fluffy. Beat in the egg yolks one at a time, followed by the vanilla extract.

4️⃣ Combine wet and dry ingredients:
Gradually add the dry ingredients to the creamed butter mixture, alternating with the buttermilk. Begin and end with the dry ingredients. Stir until just combined. Fold in the shredded coconut and chopped pecans or walnuts.

5️⃣ Whip the egg whites:
In a clean mixing bowl, beat the egg whites until stiff peaks form. Gently fold the whipped egg whites into the cake batter until well incorporated.

6️⃣ 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. Let the cake cool completely in the pan on a wire rack.

7️⃣ Make the frosting:
In a mixing bowl, beat the softened butter and cream cheese together until smooth and creamy. Gradually add the powdered sugar, one cup at a time, mixing well after each addition. Stir in the vanilla extract.

8️⃣ Frost the cake:
Once the cake has cooled completely, spread the cream cheese frosting evenly over the top. Garnish with additional shredded coconut and chopped pecans or walnuts, if desired.

9️⃣ Serve and store:
Slice the Italian Cream Sheet Cake into squares and serve. Store leftovers in an airtight container in the refrigerator for up to 5 days.