Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans by greasing them with butter and dusting with flour.

Whisk together the all-purpose flour, baking powder, baking soda, ground cinnamon, ground nutmeg, and salt in a large mixing bowl.

In a separate bowl, beat together granulated sugar, large eggs, and vegetable oil until smooth.

Gently fold in the finely shredded carrots and the drained crushed pineapple into the wet mixture.

Gradually add the dry ingredient mixture into the wet ingredients, folding until just combined.

If using, gently fold the chopped walnuts into the batter.

Divide the cake batter evenly between the prepared pans and smooth the tops.

Bake for 30-35 minutes, or until a toothpick comes out clean.

Remove the cakes from the oven and let cool in the pans for 10 minutes before transferring to wire racks.

In a medium bowl, beat together softened cream cheese and butter until smooth, then gradually add powdered sugar and vanilla extract.

Once the cake layers have cooled, spread frosting on top of one layer, add the second layer, and frost the top and sides.

Serve and enjoy with fresh fruit or whipped cream.