Line 2 (9-inch) round cake pans with wax paper; lightly grease and flour wax paper. Set pans aside.
Stir together flour, soda, salt and cinnamon. Set aside.
Beat eggs, sugar, oil, buttermilk and vanilla at medium speed with an electric mixer until smooth. Add flour mixture, beating at low speed until blended. Fold in carrot, coconut, pineapple and walnuts.
Pour batter into prepared cake pans.
Bake at 350° for 25 to 30 minutes or until a wooden pick inserted in center comes out clean.
Make the Buttermilk Glaze
While cake is baking, make the buttermilk glaze. Bring first 5 ingredients to a boil in a large Dutch oven over medium-high heat. Boil, stirring often, 4 minutes. Remove from heat, and stir in vanilla.
Immediately after removing cake from the oven, drizzle Buttermilk Glaze evenly over cooked cake layers; cool in pans on wire racks 15 minutes. Remove from pans, and cool completely on wire racks.
Once the cake is cooled, slice each layer in half to give you a total of 4 layers. More layers = more frosting = me happy! Note: I put the 2 cake layers in the freezer for 45 minutes to make slicing them in half easier.
Cream Cheese Frosting
Beat butter and cream cheese at medium speed with an electric mixer until creamy. Add powdered sugar and vanilla; beat until smooth.
Spread Cream Cheese Frosting between layers and on top and sides of cake. I’m a BIG frosting person so I made 1 1/2 batches of the cream cheese frosting to make sure the cake was completely covered. I also sprinkled chopped walnuts in between each frosted layer to take it over the top.
I recommend storing the cake in the refrigerator when not being enjoyed.