I always say "Mow-Am" with the "mow" rhyming with "pow!" But I heard a woman saying "Here's a moam for you and a moam for you" with the "moam" to rhyme with MOAN.
My thinking is that "Mao" is like Chairman Mao...I know that's not the way to think since Maoams are not Asian sweets...but heck...how DO you say it?