I use 3X4's glued and bolted with redi rod to form the top then lag bolt a ledger to the wall and rest the front of the top on base cabinates. The top is bolted to the ledger on the wall. I then cover the works with 1/4" hardboard (masonite) as a replaceable top. I also second the overhang idea. I tried 2 layers of 3/4" plywood but found it would still deflect with heavy pounding.
Brian
Brian