A massive amount of notes and links about unreal, c++, and many other languages and technologies. The unreal notes doc was a good first read when starting to dip past the surface of the engine.

Orfeas’s site is another gold bookmark with many unique c++ tutorials for Unreal, covering some uncommonly found topics.

Formerly benui.ca — a learning site with a huge number of great Unreal tutorials and resources, mostly focused on UI, but covering a variety of topics in the engine.

A neat tutorial about creating and blending between SDFs.