For that Halloween party or simply as an autumn treat for the kids, there's no trick to this pumpkin-shaped cake.

2 (18-1/4-ounce) packages devil's food cake mix, batter prepared according to package directions
1 (4-serving) package instant vanilla pudding and pie filling
1 1/2 cup cold milk
3/4 teaspoon red food color, divided
3/4 teaspoon yellow food color, divided
2 (16-ounce) containers white frosting
4 drops green food color

Bake each batch of cake batter in a Bundt pan according to package directions. Remove from pans and allow to cool completely on a wire rack.
While cakes are cooling, in a medium bowl, whisk together pudding mix and milk. Add 1/4 teaspoon red food color and 1/4 teaspoon yellow food color to pudding and whisk until it turns orange; cover and chill.
After cakes have cooled, place 1 cake on a serving platter, flat-side up. Without cutting through bottom of cake, make a vertical cut 1/2 inch from outside edge of cake all the way around the cake, then make another vertical cut (parallel to the first one) 1/2 inch from inside edge of cake all around the cake. Gently remove cake between the 2 cuts, forming a trench, being careful not to tear bottom of cake; set aside. Fill trench with pudding.
Place other cake, flat-side down, on top of first cake, lining up edges so that it takes on the shape of a pumpkin. Set aside 1/2 cup frosting then, in a medium bowl, combine remaining frosting with remaining 1/2 teaspoon red and 1/2 teaspoon yellow food color; mix well.
In a small bowl, combine reserved 1/2 cup frosting with green food color, stirring until well blended.
Fill center hole with reserved cake pieces, allowing one long piece to stick out the top, forming a stem. Frost cake lightly with orange frosting so the lines in the cake are still visible. Frost center stem with green frosting.
Chill for at least 4 hours before serving.