Since you're posting here, you're looking for the shortcut.

The shortcut is Karpathy's "Let's Build GPT: from scratch, in code, spelled out" video:

https://www.youtube.com/watch?v=kCc8FmEb1nY

Then there is a good video that dives into LLMs and how they work that is quite approachable:

https://www.youtube.com/watch?v=7xTGNNLPyMI

From there, flesh out knowledge with his other videos, where he goes both extremely light and extremely deep:

https://www.youtube.com/@AndrejKarpathy/videos

Anyway, I really like's Karpathy's video because he's very good at explaining LLMs at every level.