There are several ways of doing this but it depends on what equipment you have. One way might be to turn a spigot on the blank to accommodate the largest chuck jaws you have. After mounting on the chuck and turning the face and sides drill a 30mm hole through the middle. Then turn a tight fitting 30mm spindle onto which to replace the work. Turn the remaining side supporting the work with the tail stock if needed. Provided the piece is a snug fit on the spindle remove the tail stock to do the final turning taking care.
Another way might be to turn the first half of the piece as before and then mount it in some wood jaws attached to your chuck to turn the second side.
I personally would not use Cole jaws or a Longworth chuck but I’m sure some turners might.
Let us know how you get on when you’ve done it as it’s always nice to see others solutions to mounting work pieces.