Design Thinking is a method used to solve problems. The Design Thinking Method is ideally suited for solving very complex problems (also known as wicked problems). People are central to the methodology by always defining problems based on human needs. Solution directions are determined with brainstorming sessions, after which you immediately make a prototype with the Design Thinking Method and test the solution in practice.
Going through the phases of the Double Diamond framework for innovation is simultaneously applying methods of Design Thinking. You can find various Design Thinking processes online, but the Double Diamond can be recognized in all processes. It doesn’t matter which process you use as long as you are aware of the fundamental building blocks of a design process. And those fundamental building blocks are beautifully displayed in the Double Diamond.