Granite breakfast bar help?

A couple of ideas. You can find plaster columns at Michael's. You can paint & faux finish them. I would put these to the front of the bar for decorative as well as support use. Lots of heights & styles to choose from. From the back, you'll need to use hefty triangular supports that will be secured into the countertop that you're extending it from. My best suggestion would be to use cabinets though. You can get them 12" wide.