John, I believe you may have actually been on the right track with Paul Winchell. Whoever it was did commercials for Nestle. The "boy" dummy would start with:
N-E-S-T-L-E-S
Nestles makes the very best
And then Farfel (also a dummy, which looked a little like a very dark dachshund) would say in a very Eeyore-like voice:
Chocolate
After which, his mouth would slam shut loudly.