Domaine Guffens-Heynen is the pair's original winemaking project, set up in 1979 after they moved from their native Belgium to learn winemaking in Burgundy. The estate has five hectares (13 acres) of vineyard, including a hectare (2.5 acres) of Pouilly-Fuissé vines, and about the same of Saint-Véran. Yields are tiny, and the wines are fermented with natural yeasts, aged on their lees, and bottled without filtration.