Preheat oven to 350°.
In a mixing bowl, cream together oil and sugar. Add eggs one at a time.
Slowly add in carrots and pineapple.
In another mixing bowl, sift together baking soda, cinnamon, salt, baking powder and flour.
Add dry mixture to wet mixture and beat until smooth. Fold in 1/3 cup walnuts.
Pour batter into two lightly greased 8-inch round cake pans and bake for 25-30 minutes or until a toothpick inserted into the center comes out clean. Allow cakes to cool completely and remove from pans.
Meanwhile, in a mixing bowl, cream together butter, cream cheese and vanilla.
Slowly add powdered sugar and mix until smooth.
Trim and level cakes. Spread 1 1/2 cups frosting over the top of one cake and stack the second cake on top.
Carefully frost the entire cake with remaining frosting and garnish with remaining 1/3 cup of chopped walnuts.
To enhance the texture and flavor, replace 3/4 cup all purpose flour with 3/4 cup almond flour.