Dreams involving schools often symbolize learning and personal growth, while the setting of a cooking competition can represent feelings of competition, collaboration, or the need to showcase your skills. The fact that you were on a top floor and outside might suggest a sense of being elevated or looking at a situation from a higher perspective, possibly indicating clarity or a new viewpoint regarding your life circumstances.

The cooking of a millipede, which is an unusual and perhaps unsettling choice, could indicate feelings of anxiety or discomfort about a particular challenge you are facing. The millipede might symbolize something that you find unappealing or difficult to confront in your waking life. The black blood oozing from the judges' mouths may represent the negative consequences or reactions that come from facing these challenges or from the competitive nature of the situation.

The group dynamics and the appointment of a leader suggest themes of teamwork, leadership, and possibly the pressure to perform well in a group setting. This could reflect current situations in your life where you feel the need to collaborate with others or take on a leadership role but are also concerned about the outcomes.

Overall, this dream might be prompting you to reflect on how you handle competition and collaboration in your life, as well as how you cope with challenges that may seem daunting or unpleasant. Consider exploring any current situations that evoke similar feelings and think about how you can approach them with a more positive or constructive mindset.