Preheat oven to 350º. Spray 2 round 9-inch cake pans with cooking spray. Line bottoms with circles of parchment or waxed paper.

Whip eggs and sugar with an electric mixer until thick. Add the oil. Sift together the flour, cinnamon, baking powder, soda, and salt. Add to the egg mixture and mix well on low speed, scraping the sides and bottom of the bowl as you go. Add the carrots and walnuts. Pour the mixture into the two prepared pans. Bake until the cake springs back when touched with your finger, about 45 to 50 minutes. Cool completely.

For the cream cheese frosting: Beat the butter with an electric mixer until smooth. Scrape the sides of the bowl to make sure there are no lumps. Add the cream cheese and mix well, scraping the bowl again. Add the vanilla, salt and powdered sugar and mix on low speed. Be careful not to mix too much or the frosting will be runny.

Frost the first layer of the cake with cream cheese frosting, put on the second layer and frost. Top with the ½ cup chopped walnuts and chill before serving.