Best software to cut this part

[D-man]

Hey guys,

can anyone help in letting me know which software would be best suited to cutting the attached part. ive tred Cut3D (May be doing it wrong) but i just cant seem to figure it out. been away from the machine for a while doing this sort of stuff

Basically its a 200mm dia circle but i need to mill away the top to get the 1050mm radus cutting the rest is fine