When Boston Beer Works owner Steve Slesar put head brewer Jodi Andrews on the task of concocting a porter brewed with peanut butter, she though he was nuts.

"I said, ‘You’re crazy.’ There’s lots of fat in peanuts," Andrews explains. "Fat and beer don’t mix."

She’s referring not to waist reduction, but to head retention. The fattiness of peanut butter means a flat, oily brew. It also makes for a dauntingly messy brewing process. Nevertheless, Andrews is not one to shy away from a challenge. "I was skeptical, but I did it."

For the first batch, hoping to trim the fat, she tried a special dehydrated peanut butter. The end result was okay, but not great. "I could taste it, but didn’t get too much in the aroma." So for round two, she went for broke. Well ... not broke, exactly.

"I walked over to Brooks Pharmacy and found some of that Teddie Peanut Butter. It was on sale."

Eureka! By adding that discount viscosity to the boiling kettle, and again in the conditioning tank, Andrews struck black gold. One would be forgiven for thinking that a PB-flavored beer might be a little ... much. But this one is imbued with a subtle nuttiness that’s present more in the aroma than the flavor. And the peanut butter gives the stuff a pleasingly lubricious, nearly chewy consistency (it’s also a joy to look at, pouring from the tap almost like stout, dissipating and settling in a gorgeous brown-black ballet).

And the porter is the ideal style for the job, with burnished nut flavors perfectly complementing the chocolaty overtones of its roasted dark malt. If you’re a fan of robust brown ales or dry stouts, this is one you should try — unless you’re allergic to nuts.

"You can brew beer with anything," Andrews says. "It’s just a matter of making it taste good." Mission accomplished.

Available for $4 for a pint and $11.95 for a 64-ounce growler at Boston Beer Works, 61 Brookline Avenue, Boston, (617) 536-2337; and 112 Canal Street, Boston, (617) 896-2337.