Preheat oven to 350 degrees. Generously grease two 23 cm cake pans; set aside. Sift flour, baking soda, cinnamon and salt together; set aside. In a large bowl, beat eggs. Add oil, buttermilk, sugar and vanilla; mix well. Add flour mixture, pineapple, carrots and walnuts; stir well. Pour into cake pans, bake for 55 minutes or until wooden tooth pick inserted in center comes out clean. While cake is baking, prepare Buttermilk Glaze. Remove cake from oven and slowly pour glaze over hot cake. Cool cake in pan until glaze is totally absorbed, about 15 minutes. Turn out of pans, and cool completely. Prepare Cream Cheese Frosting; frost top of one layer first, then set the other layer on top of that, frost sides and top. Refrigerate until frosting is set. BUTTERMILK GLAZE: In a small saucepan, combine sugar, baking soda, buttermilk, butter and corn syrup. Bring to a boil. Cook 5 minutes, stirring occasionally. Remove from heat and stir in vanilla. CREAM CHEESE FROSTING: Cream butter and cream cheese until fluffy. Add vanilla, powdered sugar, orange juice and grated peel. Mix until smooth.