Combine flour, baking soda, cinnamon and salt in a small bowl. Combine milk and lemon juice in liquid measuring cup (mixture will appear curdled).
Beat granulated sugar, pumpkin, eggs, brown sugar and vegetable oil in large mixer bowl until combined. Beat in pineapple, carrots and milk mixture until combined. Gradually beat in flour mixture. Stir in coconut and 1 cup walnuts or pecans. Pour into 2 greased 9-inch round cake pans.
Bake preheated 350F oven for 30-35 minutes or until wooden pick inserted comes out clean. Cool in pans on wire rack for 15 minutes. Remove to racks to cool completely.
In small mixer bowl whip the 2 cans of cream cheese frosting to make it light and fluffy. Frost cake when cool. Garnish with chopped pecans or walnuts.