Someone Left The Cake Out In The Rain—Mystery Solved

I have wondered for decades if the the lines

"Someone left the cake out in the rain
And don't that I can take it
'Cause it took so long to make it
And I'll never have that recipe again"

were a joke. I found the answer!

https://waynerobins.substack.com/p/jimmy-webb-the-meaning-of-macarthur