Preheat your oven to 350°F (175°C) and line a muffin tin with colorful cupcake liners.

In a large mixing bowl, whisk together eggs, brown sugar, neutral oil, sour cream, and mashed pineapple until smooth.

In a separate bowl, sift together flour, baking powder, baking soda, cinnamon, and salt.

Gradually incorporate the dry ingredients into the wet mixture, folding gently; add shredded carrots and nuts.

Spoon the batter into cupcake liners, filling each about ¾ full, and bake for 18-20 minutes.

Allow cupcakes to cool on a wire rack for 10 minutes before transferring them to cool completely.

Prepare walnut crumble by mixing walnuts, flour, brown sugar, and salt; add butter and blend until crumbly.

Bake walnut crumble at 320°F (162°C) for 20 minutes, then let cool.

Beat cream cheese, powdered sugar, vanilla, and salt until smooth; gradually add heavy cream until soft peaks form.

Frost the cooled cupcakes with cream cheese frosting and top with walnut crumble.

Refrigerate frosted cupcakes for at least 30 minutes before serving.