Cut the Cevenne onions in half and clean them. Now slice them in thin slices.
Add a drizzle of oil to a hot pan and start glazing the onions with the salt. Continue heating the onions on a medium low heat till all have softened.
Once completely softened add the cream and also add the butter, the bay leaves and the apple cider vinegar. Keep on heating till almost all the liquid has reduced.
Then remove the bay leaves and transfer everything into a blender. Blend this till smooth. This takes a couple of minutes.
Once smooth add a knife tip of xanthan gum and blend it for another minute. The xanthan gum will prevent the cream from leaking once plated.