We're excited about Mustachio, a templating language developed by the Postmark team to enhance their Templating experience. The goal was to create an approachable and natural experience for developers and designers, with an editing environment that minimizes context switches between template editing and external code editors. To achieve this, we extended the Mustache language to add features such as Model Inference, which detects dynamic content in templates and provides a reference model, and Complex Keys, which allows for more concise markup and traversal of data models. We deliberately chose not to include features like partials or helpers in our initial release, instead opting for a focused approach that ensures the added complexity is manageable and defect-free. By building Mustachio from scratch, we can leverage the team's skill sets, reduce operational complexity, and increase code sharing among team members. The final result is a great templating language solution that enhances the Postmark Template experience.