Putting in a plug for MIT OCW 8.962 [1]. I also had this itch, and was able to find time during the pandemic to work through the course (at about 1/2 speed). But true to what others are saying, life intruded for the last few lectures, so still have some items on my todo list. I thought Scott Hughes laid out the math with terrific clarity, with just the right amount of joviality. It is not for everyone, but if you have a suitable background it may turn "scratch an itch" into the obsession that it has done to me.

And to make the obligatory on-topic comment: I'm 61yo. Now get off my lawn.

[1] https://ocw.mit.edu/courses/8-962-general-relativity-spring-...