This is the most effective UX case study format I have figured out in my 5 years of experience in product design.

A UX case study tells the story of how you improved the user experience (UX) of a product. It highlights the problem users faced, your research to understand their needs, the design solutions you created, and the positive impact those solutions had. Think of it as a mini-documentary showcasing your design thinking process and the success of your efforts.

Enjoy :)