I'll have to go back and listen again, but was Boozoo really using the "ne ... pas" construction? That would be very unusual in Louisiana French.
I don't think this line should be understood as
"Elle m’a fait des biscuits, et (elle) n’a pas de sirop" (ne ... pas), but as "elle m'a fait des biscuits et (i) n-a pas de sirop", with the "n" for "y".
(i)n-a pas de sirop = y a pas de sirop.
(You can find more examples of this construction in the DLF, entry "avoir").
I have always wondered about that, and we've discussed it at length in other forums. Couldn't understand if it was an old hold out from the "ne pas", or a shortening (and maybe misuse?) of "y en a pas..". Regardless, I heard it a lot growing up.
Yes, the liaison (y en a / y en a pas) or the negative with n' (y en n'a pas) make the same sound. Both probably merged into the "i-n-a / i-n-a pas" form. (I'm just guessing).