The European Health Data Space (EHDS) Regulation aims to enable efficient cross-border discovery, access, and secure reuse of electronic health data (i.e. sensitive and non-sensitive datasets) for research, innovation, and policymaking. To meet EHDS regulatory requirements, Health Data Access Bodies (HDABs) are obliged to maintain an interconnected public national dataset catalogue and health data holders must provide standardised descriptions of datasets, with the aim to enable efficient discovery and interoperability across Europe. While the DCAT Application Profile (DCAT-AP) is widely adopted for general data cataloguing across the EU due to its robustness and simplicity, its generic scope lacks essential health-specific metadata elements which are required to assist the implementation of the EHDS, such as data sensitivity levels, access regulatory procedures, health-specific terminologies, and quality annotations. This paper presents the EHDS-related extension of the DCAT Application profile (HealthDCAT-AP) case study, detailing how a domain-specific extension of DCAT-AP was designed to address these gaps. It outlines the methodological approach involving use-case analysis, careful requirements definition, and stakeholder engagement, which resulted in a concise and interoperable fit for purpose metadata extension. The resulting HealthDCAT-AP, validated through a multi-country pilot implementation, followed by a refinement and validation phase and a pan-European public consultation, demonstrates a practical blueprint for other specialised DCAT-AP profiles across domain-specific European data spaces.