Decorate cake. Prepare decorating bags separately with tips 12, 5 and 1. Fill tip 1 bag with small amount ivory icing. Divide remaining ivory icing evenly between tip 12 and tip 5 bags. Repeat entire step with black icing and remaining tips.
Using bags with black icing and tips 12 and 5, pipe trees and branches on ivory tier. Using bag with tip 1 and ivory icing, pipe details on trees and branches.
Using bags with ivory icing and tips 12 and 5, pipe trees and branches on black tier. Using bag with tip 1 and black icing, pipe details on trees and branches.
Using tip 12 and ivory icing, pipe mound of icing at bottom, middle and top of cake. Use mound to hold food-safe flowers and sage leaves. Insert uncooked spaghetti noodle into cranberry; insert into cake. Repeat with desired amount of cranberries.