Preheat & Prepare – Preheat oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper and lightly grease it.

Make the Batter – In a bowl, whisk together flour, baking powder, baking soda, cinnamon, nutmeg, and salt. In another large bowl, beat together sugars, oil, eggs, and vanilla until smooth. Fold in the dry ingredients, then stir in carrots, walnuts, and pineapple until just combined.

Bake – Spread the batter evenly in the prepared pan. Bake for 15-18 minutes or until a toothpick comes out clean. Let it cool for 5 minutes, then transfer it onto a clean kitchen towel.

Roll the Cake – While still warm, gently roll the cake (with the parchment paper) into a log from the short side. Let it cool completely in this shape to prevent cracking later.

Make the Frosting – Beat cream cheese and butter until creamy. Gradually add powdered sugar and vanilla, mixing until smooth.

Assemble Vertically – Unroll the cooled cake and cut it into three equal strips lengthwise. Spread a layer of frosting on each strip. Start rolling the first strip tightly, then attach the second strip where the first ends, continuing to roll. Repeat with the third strip. Place the cake upright so the spiral is vertical.

Frost & Decorate – Spread frosting all over the cake. Decorate with walnuts, coconut flakes, or carrot decorations if desired. Chill for at least 1 hour before serving for easier slicing.