PREHEAT oven to 350° F. Prepare three 6-inch round cake pans.
BEAT cake mix, water, eggs and oil in large mixer bowl on low speed for 30 seconds. Beat on medium speed for 2 minutes or until smooth. Divide batter equally among three pans and bake for 18-22 minutes.
REMOVE cake from oven and rest in pan for 5 minutes. Invert onto cooling rack and allow to come to room temperature. When ready to assemble, stack one layer on cake stand and cover with ¼ cup frosting. Repeat with all layers. Use remaining frosting to cover outside of cake. You may need to chill cake and add another layer of frosting to get a crisp, clean look.
POUR ¼ cup of NESTLE® TOLL HOUSE® Semi Sweet Morsels into a plastic disposable bag. Secure with rubber band and heat in microwave for 30 seconds. Massage chocolate after heating. If all morsels are not melted, heat in 10 second increments until fully melted.
CUT off a small tip from the bag. Pipe out an evergreen tree shape onto a cookie sheet lined with parchment paper. You will want to pipe out enough for the entire cake.
CHILL chocolate trees until solid. Gently place trees around edge of cake. Chill until ready to serve.