This is a Sous Voile wine, which is a method the Jura region is famous for mastering.
Usually made with Savagnin but also made with other white grapes like Chardonnay, Sous voile means “under a veil,”
Sous Voile is essentially where a layer (or veil), of yeast forms on the surface of white wine as it ages in barrel.
During the maturation process, the barrel is not filled full or topped up, leaving space for the wine to be exposed to oxygen.
Once the veil forms, it generally protects the wine from oxygen, and nutty flavors, spices, and floral aromas develop as well.
Jura’s Vin Jaune is made like this, but many producers in the region make Savagnin sous voile by removing it at some point from Vin Jaune aging, to not be as intense.