Bake a sheet cake the size that you need.
With an icing filled bag and round tip, size #5, draw the pumpkin shape on the top of the cake. Cut the cake away from the pumpkin shape.
Make a yellow colored icing and using star tip, size #18, fill in the eyes, nose, and mouth of the pumpkin.
Make a light green colored icing and using the same
size star tip, #18, put the veins on the leaves. Refer to the pictures.
Now make a darker green icing and use the same size star tip, #18 to
fill in the rest of the leaves.
Make a medium brown colored icing and use the same size star tip, #18 to cover the stem of the pumpkin.
Make a smaller amount of darker brown icing and use round tip, size #5 to pipe the lines on the stem.
Now make orange icing and cover the rest of the pumpkin using the same size star tip, #18.
Use the same orange icing and round tip, size #5 to
outline the eyes, nose, mouth and vertical lines on the pumpkin body.
Finally, you can use either the medium or darker brown icing and round
tip, size #5 and draw the vines on either side of the stem.
Note: If you want to make a fatter pumpkin, just use a large round cake pan instead of a sheet cake pan.