This is actually very simple to do. Here are the steps:
1/ open AI
2/ draw a perfect circle, add gradient color. copy and paste
3/blend-choose steps 500 (add more if you like, this will decide how smooth the surface looks)
4/ draw an M, then choose M and what you get from step3, object-blend-s
5/Ta Da, here it is.
It has been a while since my last update. Kinda busy on preparing exams. Have a great time, exploring, everyone.