I made 2 9×13 cakes and used green dyed buttercream icing. The yellow brick road is yellow fondant that I scored like bricks and let it dry the day before. Next time, I would make it longer.
The pond is blue icing gel. The grass is coconut dyed green using a Ziploc bag to shake the dye and coconut together. Use gloves to apply! The witch legs are candles with fondant wrapped for the shoes. The house is graham cracker with icing as glue. The gumdrop trees are dots with toothpicks.
Finally, we wanted some rainbow representation, so we got these sour gummy strips and twisted them and anchored with toothpicks.