This trial is testing a new treatment called Mindfulness-Based Cognitive Therapy (MBCT) for people with Obsessive-Compulsive Disorder (OCD) who haven't fully benefited from standard treatments. MBCT helps patients become more aware of their thoughts and feelings without reacting to them, which can reduce OCD symptoms. If successful, this approach could be used widely in clinical settings to help more people with OCD. Mindfulness-Based Cognitive Therapy (MBCT) has been shown to be effective in various mental disorders and is now being explored as a complementary treatment for OCD, particularly for those who do not fully benefit from standard treatments.