15" is the minimum recommended for a seating overhang at counter height. You can purchase metal support brackets, but the plywood sub-top would need to be removed to use the ones I've seen.

Images--support brackets

NKBA guidelines (overhang recs)

agree about the electrical. (unless there is an outlet somewhere on top?)

but taking it down and making it level isn't a big deal. they (the installers) should install the steel bracing. 12-15" would be fine)

consider finishing the side panel, and the front.

or do a one side waterfall

You might not be required to bring it up to code with the electric if you're just doing cosmetic upgrades and nothing that requires a permit.

Extra outlets are always nice to have, though. But if you have work done to add them, you might be required by code to upgrade lots of things you hadn't planned on upgrading.

I don't have an outlet in the end of my peninsula, which I love, because it would have cut a hole in my walnut. The code calls for way too many outlets IMO (code written by electricians ;)

Yes it's doable. I'd cut the the raised part flush, then run 1" square tube flush with the cabinet tops from the back of the cabinet fronts and across the rear of the wall/cabinet, extending about 3" short of any countertop overhang. Paint the exposed ends flat black, cap the ends, and they'll be inconspicuous. Get the electrical updated first please.

"I don't have an outlet in the end of my peninsula, which I love, because it would have cut a hole in my walnut. The code calls for way too many outlets IMO"

My experience has been that the codes came into effect when morons kept using extension cords for electrical coffee pots, toasters, and other small electrical appliances. I confess I was almost enticed to string a cord from a free standing dining room table to the wall to keep a buffet dish hot. Sense prevailed and I didn't. But I understand the inclination.

Thank you everyone for The comments! home was built in 2000, and there is a plug on the wall 2” from the bar top. We are only replacing a ceramic tile counter top w/ granite. All the pictures I’ve seen for new homes do not shoW outlets. i have a plug very close. Is this code in all states?

Additionally, this bar top is connected to other cabinet that runs along a wall. So it’s the long part of an “L” shape.

We just completed project of cutting our 42”high , 10’ long angled island to counter height. electric was in riser of island, now is in both sides. Plug ins both sides & island light switch on one side. We had granite, changed to quartz, had corbels, changed to steel brackets underneath counter so invisible. Our island back has several layers, cabinet/ wallboard/ beadboard back. Electrician told us code here in Vancouver WA is for outlets each 2’ on perimeter counters, which we had as our home built 2012. 15” is the standard for counter height overhang but we wanted the same “aerial ” footprint as our bar height island had so we maintained the 13.5” overhang & it‘s enough space that no one is knocking knees on island back. I think the rule is, the lower the eating surface, the wider the overhang. That’s why we didn’t want to have corbels again too. Also, the solid big piece of quartz weighs much more the the 19” wide piece of granite that was the bar top.