We introduce MINTly, a theory-based system designed to enhance cognitive engagement through interactive learning activities. While engagement is a critical factor for learning success, it is often low in digital learning environments. However, such environments hold great potential for supporting teachers in managing large, heterogeneous classes and offering students more personalized learning experiences. MINTly is built on educational theories to foster higher levels of learning engagement. It allows learners to learn in all four engagement modes of the ICAP framework, with a particular focus on interactive activities, which, according to the ICAP theory, are especially effective in promoting learning. The system supports both teachers and students. It organizes classes, groups of learners, and learning materials efficiently while enabling students to collaborate with peers and seek additional help from teachers or integrated generative AI services. In this paper, we present the design, functionality, and application of MINTly, highlighting how it can promote engagement and support effective learning in diverse educational settings.