Preheat your oven to 350°F (175°C) and prepare two 9-inch cake pans by greasing them with butter or oil and lightly dusting with flour, or line them with parchment paper for easy removal.

In a large mixing bowl, whisk together 1 cup of granulated sugar, 1/2 cup of brown sugar, 3 large eggs, 1 cup of vegetable oil, and 2 teaspoons of vanilla extract until the mixture is smooth and well combined.

Gently stir in 2 cups of grated carrots and 1 cup of drained crushed pineapple into the wet mixture.

In a separate bowl, whisk together 2 cups of all-purpose flour, 1 teaspoon of baking soda, 1 teaspoon of baking powder, 1 teaspoon of ground cinnamon, and 1/2 teaspoon of salt. Gradually mix these dry ingredients into the wet mixture.

If desired, gently fold in 1/2 cup of chopped walnuts.

Carefully divide the batter evenly between the two prepared cake pans, smoothing the tops with a spatula.

Place the cake pans in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, allow the cakes to cool for about 10 minutes in the pans. Then, transfer them to a wire rack to cool completely.

In a mixing bowl, beat together 8 ounces of softened cream cheese and 1/2 cup of softened unsalted butter until the mixture is creamy and smooth. Slowly add in 4 cups of powdered sugar, mixing until fluffy.

Stir in 1 teaspoon of vanilla extract and, if desired, a splash of pineapple juice.

Place one layer of cooled cake on a serving platter and generously frost the top. Add the second layer on top and frost the top and sides of the entire cake.

For a final touch, garnish your cake with additional chopped walnuts or fresh pineapple slices on top.