Several years ago I had the chance to visit the astonishing collection  of the Städel Museum in Frankfurt. In the picture: the Flémalle Panels: Saint Veronica, Virgin and the Child, Throne of Mercy.  These artworks are now attributed to the workshop of Robert Campin (the exact attribution is disputed even today) and they are among the most important works of early Netherlandish painting. For more info: https://sammlung.staedelmuseum.de/en/work/the-flemalle-panels-st-veronica-with-the-veil