Preheat oven to 375°F (190°C) and line a 12-cup muffin tin with paper liners.

Whisk flour, baking soda, baking powder, salt, cinnamon, ginger, and nutmeg in a medium mixing bowl.

In a separate large bowl, whisk together vegetable oil, granulated sugar, brown sugar, eggs, and vanilla extract until emulsified.

Fold the grated carrots and drained crushed pineapple into the wet ingredient mixture.

Incorporate the dry ingredients into the wet mixture using a spatula until no dry streaks remain; fold in chopped walnuts.

In a small bowl, whip the softened cream cheese and powdered sugar until smooth for the topping.

Distribute the batter evenly across the 12 muffin cups.

Deposit one teaspoon of the cream cheese mixture onto the center of each muffin and use a toothpick to create a marbled swirl.

Bake for 20 to 25 minutes or until an internal temperature of 200°F-205°F (93°C-96°C) is reached or a toothpick comes out clean.

Allow muffins to rest in the tin for 5 minutes before transferring to a wire rack for final cooling.