Answer:
you could do
chocolate,fudge,chocolate
chocolate,marshmallow,rainbow
chocolate,marshmallow,chocolate
chocolate, fudge,rainbow
vanilla, fudge,chocolate
vanilla, fudge,rainbow,
vanilla,marshmallow,rainbow
vanilla marshmallow,chocolate
strawberry,fudge,chocolate
strawberry,fudge,rainbow
strawberry,marshmallow,chocolate
strawberry,marshmallow,rainbow