Preheat your oven to 350°F (175°C). Grease two 9-inch cake pans with butter or cooking spray and line the bottoms with parchment paper.

In a bowl, whisk together all-purpose flour, baking soda, baking powder, cinnamon, and salt until combined.

In another bowl, mix granulated sugar, brown sugar, eggs, and vegetable oil until smooth. Stir in vanilla extract.

Fold in grated carrots and crushed pineapple until evenly mixed.

Gradually add dry ingredients to the wet mixture, folding gently until just combined.

Pour the batter evenly into prepared pans and bake for about 35 minutes, or until a toothpick comes out clean.

Let the cakes cool in pans for 10 minutes, then transfer to a wire rack to cool completely.

Beat cream cheese and butter until smooth, then gradually add powdered sugar and mix until fluffy. Stir in vanilla extract and optional pineapple juice.

Once cooled, frost the first layer of cake, add the second layer, and frost the top and sides.