Today in secret menu items: 4505 Burgers & BBQ on Divisadero is offering an artery-clogging take on the classic Big Mac: two beef patties lovingly caressing a block of fried macaroni and cheese.

Risking possible trademark infringement, 4505's Big Mac has been an secret menu staple available to those in the know at the Ferry Building for awhile now. It's a double version of 4505's Best Damn Cheeseburger, with an order of Frankaroni (fried mac & cheese, itself stuffed with bits of 4505 hot dogs) stuck in the middle. The whole thing is topped with lettuce, tomato and onion piled on a buttery pan de mie bun. You still won't find it on the menu board at the new spot, but Ryan Farr and company will gladly serve you one for a whopping $18. We recommend consulting your cardiologist before consuming.

Oh, and by the way: we're told that, like any good burger joint, the Big Mac isn't the only secret menu item on offer at the new Divisadero spot. The others, however, you'll just have to figure out for yourself. Or wait for more hints to drop on Instagram.

Previously: All Important Hamburger News on SFist
New BBQ: 4505 Burgers & BBQ and Smokestack Both Now Open