Preheat oven to 350°F. Line two standard muffin tins with paper liners (recipe makes about 20 cupcakes).

In the bowl of a stand mixer fitted with the paddle attachment, combine granulated sugar, vegetable oil, vanilla extract, and eggs. Beat on medium-low speed until the mixture turns light yellow and well blended, about 3 minutes.

In a separate medium bowl, sift together the all-purpose flour, ground cinnamon, nutmeg, baking soda, and kosher salt.

Add the chopped walnuts, grated carrots, and crushed pineapple. Continue mixing on low speed until evenly distributed.

Scoop the batter into the prepared liners, filling each about ¾ full for a nice domed top.

Bake for 24 minutes, or until the tops are golden brown and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Transfer the muffin tins to a wire rack. Let cupcakes cool in the tins for 5 minutes, then gently remove them to the rack to cool completely before frosting.

Add the confectioners' sugar one cup at a time, mixing well after each addition. Continue until the frosting is light, creamy, and spreadable.

Spread or pipe the frosting generously onto the cooled cupcakes.