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

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

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

Gently combine the wet and dry ingredients, then fold in shredded carrots and nuts.

Fill cupcake liners about three-quarters full, then bake for 18-20 minutes until a toothpick comes out clean.

Allow cupcakes to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.

Pulse walnuts, flour, brown sugar, and a pinch of salt in a food processor, then add butter and mix until sandy texture.

Spread walnut mixture on a baking sheet and bake at 320°F (162°C) for 20 minutes, stirring halfway.

In a bowl, beat together cream cheese, powdered sugar, vanilla extract, and a pinch of salt until smooth. Add cold heavy cream and whip until stiff peaks form.

Frost cooled cupcakes with cream cheese mixture and press walnut crumble onto the sides. Decorate as desired.

Chill frosted cupcakes in the refrigerator for at least 30 minutes before serving.