Preheat oven to 350 degrees. Grease 2 9-inch round cake pans and line the bottom of each with parchment paper.
In a small bowl, whisk together flour, baking soda, cinnamon, and salt. Set flour mixture aside.
Combine milk and lemon juice in liquid measuring cup (mixture may appear curdled).
In a large mixing bowl, combine brown sugar and granulated sugar. Beat in pumpkin, eggs, and oil until combined.
Mix in pineapple, carrots and milk mixture until combined.
Gradually add in the flour mixture and beat until just combined. Don’t over beat.
Fold in coconut and 1 cup chopped walnuts.
Divide batter evenly between two greased 9-inch round cake pans. Tap pans on the counter to get rid of any air pockets.
Bake at 350 degrees for 30 to 35 minutes, or until edges are golden, and a toothpick inserted near the center comes out clean.
Cool in pans for 10 to 20 minutes, then remove to wire racks to cool completely.
Don’t forget to remove the parchment paper from the tops of each layer.
Meanwhile, prepare cream cheese frosting.