Having students work in small groups has been shown to promote better student outcomes, even in large lecture classes. On an institutional scale, the creation of learning communities that span multiple classes has also been proven to improve student outcomes. Research has shown that both interventions can help narrow the performance gaps that are often observed for students from certain demographic backgrounds. However, both have their drawbacks. When used solely for discussions in class, students in small groups rarely continue working together outside lecture in an intentional manner. Grading based on group performance leads to the perception of unfairness due to "weak" or "poor" members or disproportionate workloads. Learning communities, on the other hand, require a fair amount of administrative support to implement. Here, we describe a novel course and incentive structure that allows individual instructors to create sustainable learning communities in their classes. This course structure is relatively easy to implement, requiring very few changes to existing courses, and is adaptable to a variety of contexts, including remote teaching. Finally, we show that such learning communities provide additional learning gains for students and demonstrate that these class-based learning communities help narrow performance gaps for minoritized students.