Cut the onions in slices with the already cutted side orthogonal to
the board.
Cut the mushrooms in to cubes, roughly 1.5 cm each side.
Heat some butter in a pot on high heat.
As soon as the butter melted, add the onions and stir.
After roughly 5 minutes add the mushrooms.
Caramelize the together, this takes around 30-45 minutes. Stir from
now and then and add butter if necessary. It is expected that there is
some debris on the bottom of the pot. Nothing to worry about.
After roughly 20 minutes add a small sip of white wine to solve the
debris in it. Let it reduce immediately and continue caramelizing.
After further 20 minutes, add around 50-100 ml of white wine and let
it reduce. This gives the nice creamy texture to the mushrooms.
Shortly before you serve, add the chopped parsley on top.
