• Preheat the oven to 350°F and grease two 8 or 9-inch round cake pans. Line the bottoms with parchment paper and spray with nonstick cooking spray.

For the cake batter

• Whisk flour, baking soda, baking powder, salt, and cinnamon in a medium bowl.
• Whisk the oil, granulated sugar, brown sugar, and vanilla in a separate bowl. Then, whisk in the eggs, one at a time, until fully combined.
• Gradually add the flour mixture to the oil mixture in three parts, scraping the sides of the bowl as needed after each addition. Stir gently until the batter is smooth, then fold in the carrots, nuts, and raisins.

Baking the cake

• Divide the batter equally between the prepared cake pans. Then bake until the tops of the cake spring back when touched and when a toothpick inserted in the middle comes out clean; about 35-45 minutes.
  
• The cakes should cool in the pans for 15 minutes before carefully turning them out onto a metal rack. Then, peel the parchment lining from the cakes and cool completely.
  

For the cream cheese frosting

• In the bowl of a stand mixer fitted with the paddle attachment or in a large mixing bowl using a hand-held mixer, beat the room-temperature cream cheese until smooth. Add the softened butter and beat until well mixed, about 30 seconds to 1 minute. Add the powdered sugar and vanilla extract and continue mixing until fully combined and smooth. Scape the sides of the bowl as needed.

Assembling the cake

• When the cake layers are completely cool, place one of the layers on a cake stand. Top evenly with a heaping 1/2 cup of frosting with a butter knife or offset spatula. Place the second layer over the top and use the remaining cream cheese icing to frost the top and sides of the cake. Top with chopped nuts in the center if desired.