How do you pronounce "often"?

This quote is from Throw Grammar from the Train:

"Sounding the t in often." I've been interested in this one since my daughter, brought up as an OFF-en speaker, went to college at the University of Michigan and came back saying OFF-ten. I don't think it's a regional thing -- I grew up two hours south of Ann Arbor, and I don't remember OFF-ten even as a variant. It must have been something she picked up from friends. ... And it's true that OFF-ten deviates from the usual pattern of soften, listen, fasten, christen, etc. 

Read that last sentence again and notice that the "T" sound is silent in lots of the words we use ... (ah-hem) ... OFTEN.