Since you took the time to cut all those incisions in the shells, the roasted chestnuts will be relatively easy to peel. They will also, however, be hot. And here we have the real trick of getting a freshly roasted chestnut into a state in which you can eat it. If you let them cool too much, they get more difficult to peel as the skin inside the shell seems to re-attach itself to the nut. I like to wrap them in a clean kitchen towel to keep them warm.
Pull and snap off the shell, being sure to take the skin inside the shell with it.
At my house, we like to sit around a pile of freshly roasted chestnuts, each taking a nut, peeling it, and eating it as we chat and this and that. You may, however, have other plans for those chestnuts (candied? stuffing? soup? garnishing a cake?), in which case you may need to settle in a peel them all yourself.