Ask HN: Resources for learning about type-checkers?

Can HN kindly recommend resources for learning how type-checkers work?

I'm looking for entry-level resources geared towards curious engineers. I have tried to read a number of academic articles on the subject, but I think I am lacking some concrete grounding to make sense of the theory.

As such, the ideal resource would involve implementing a non-trivial type checker. A live-coding course similar to [0] would be ideal, but I will happily accept video lectures, books, blog articles, or any other format.

Many thanks in advance!

[0] https://youtu.be/7pLCpN811tQ