Mix cake according to manufacturer’s instructions. Measure out 3 pounds batter, deposit 1 pound into a sprayed and papered 8-inch cake pan. Repeat two times to make 3 cakes total. Bake at 350 ͦF until cake springs back lightly when touched. Let cool completely.
Place one cake round on a cake board, pipe buttercream around the edges. Using a #8 grey scoop, place one scoop pumpkin filling on the cake round and spread to edges and place another cake round on top. Repeat with the next layer, again using pumpkin filling and top with remaining cake round. Place internal supports/dowels into the cake. Crumb coat with buttercream, smooth ice, reserve. Place buttercreme in three bowls, add orange and brown food coloring to one bowl to make a muted orange color. Place leaf green and brown food coloring to another bowl to make sage green. To the last bowl, add a small amount of navy blue food coloring to make a muted blue color. Place the orange and blue buttercremes in piping bags fitted with open star tips. Place the green buttercreme in a piping bag fitted with a leaf tip. Pipe alternating orange and blue pumpkins on the sides and top of cake using pretzel rods as stems. Sprinkle with gold crystal sugar.