[runjake]

Programming Windows and Inside Windows are the books you want.

Programming Windows covers systems programming in C and in later editions, in C#.

Inside Windows goes over the Window OS architecture in-depth. There’s not much programming in the book but you will come away with a deep understanding of the OS.

Both books are published by Microsoft Press. You’ll of course want the latest editions but if you come across earlier editions, those are fine too.

I’m partial to the earlier Petzold editions of Programming Windows.

The technical docs at microsoft.com are also super helpful and up-to-date: https://learn.microsoft.com/en-us/docs/