This article presents an extension of the well-known TPACK model to describe the professional digital competencies of mathematics teachers. The extension leads to what we want to call MPC-model (Media-Pedagogy-Content) in the following. It additionally includes (1) the consideration of competencies instead of knowledge for a holistic description, (2) the integration of professional digital competencies in a broader context of professional media competencies (including explicitly analog and digital teaching media), (3) the description of concrete individual experiences with digital technology in context-bound subjective domains of experience, and (4) the cross-linking of concrete individual experiences about (digital) technology in specific (subjective) domains of experience. In this article, we first present a motivating literature overview leading to the research question: How can the TPACK model be extended to enable a qualitative description of professional digital competencies of mathematics teachers against the background of situated experiences? This extended framework is developed and presented in a detailed theoretical background. In the empirical part of the article, an exemplary application of the MPC-model is carried out in an explicative case study dealing with the reflections of a mathematics teacher on a planned lesson using virtual reality technology in a guided interview. The qualitative data is interpreted according to the systematic-extensional analysis method. The case study illustrates the importance of taking into account concrete situated experiences opening up a new reflective level analyzing the development of professional mathematics-specific digital competencies.