Preheat the oven to 350°F and prepare two 9-inch round cake pans by greasing, lining with parchment, and greasing again or flouring.
Whisk together flour, baking soda, salt, and cinnamon in a medium bowl.
In a separate bowl, combine vegetable oil with both sugars and vanilla extract.
Whisk in eggs one at a time into the sugar mixture.
Fold in the dry ingredients gradually until the batter is smooth, then stir in grated carrots, pecans, and raisins.
Divide the batter evenly between the prepared pans and bake until a toothpick comes out clean, about 35 to 45 minutes.
Allow cakes to cool in pans for 15 minutes, then transfer to wire racks to cool completely.
For the frosting, beat cream cheese until smooth, then gradually add powdered sugar and cornstarch, followed by heavy cream, beating until whipped and creamy.
Assemble the cake by frosting the top of one layer, adding the second layer, and then frosting the top, leaving the sides bare. Sprinkle with chopped pecans.