Absolutely delightful, excellent, or delicious in the extreme. Referring more to thought and form, than to flavor. (Root word: scrumptious Source: Saturday Night Live, "The Actor's Guild")
His on stage antics weren't just amazing, they were scrumptulescent, transcending all levels of excellent.
The only word suitable to describe the utter greatness of Charles Nelson Riley and his performances, as invented - ad hoc - by James Lipton (Will Ferrell), because all other words were, and are, completely inadequate.
There is no word powerful enough to describe your Charles Nelson Riley's performance, so I am forced to make one up, and I will do so right now: scrumptrulescent