I went to lecturers that I liked who taught subjects that I liked in my bachelor days and asked if they would take a student.

Find another supervisor who will give you that freedom and the research topic you like. If you really like your current supervisor, you can ask yourself if you can compromise a bit and do something that he has some expertise in.

Find out what topics are on offer in other unis, then email the supervisor and set up a meeting with him/her. You can then talk to them and find out what their style of supervision is, how their funding is etc. Since you want to switch to other unis, you'll have to take your chances.

It is very important to pick the right supervisor but there are no 'perfect' supervisors. Go and 'interview' a few of them and when the time comes, pick the logical option, and then deal with your new supervisor's flaw.

I picked my supervisor because he's a nice guy and a good educator and was offering a topic that was interesting to me. The downside to picking him was that he doesn't work in the lab (cause he's already a senior lecturer/researcher) and sometimes he is too chill. Fortunately I have 3 other co-supervisors who are highly active in the lab.