Okay, I'm not in construction, I'm in the food industry. From a food safety standpoint, you want to be able to WASH your cutting board after each time you use it. E. coli 0157:H7, salmonella, listeria monocytogenes, and others are nothing to take lightly. They can cause anything from a mild case of diarrhea to death. For this reason, I suggest that you make your counter top solid, and you can have your cabinet maker build you a nice large butcher block cutting board to sit on top, but which you can carry to the sink and wash after use. If you have the marble cut out in the middle, you will only be creating places for food to collect which will be hard to clean. Of course you can do what you wish - it's your kitchen - I just wanted you to be aware of the issues you might have with sanitation and food safety.