Preheat the oven to 180°c. Peel and dice the onions and finely slice the garlic.
Place onions and garlic in a large pan on a medium-low heat with 1 tablespoon of olive oil. Strip in the thyme and cook for 10 minutes, stirring regularly.
Whilst the onions, garlic and thyme are cooking away, slice the mushrooms and tear the sourdough bread into 4cm chunks.
Stir the mushrooms into the pan, pour in the stock and bring to a boil.
Add the bread then grate in most of the cheese. Stir well then transfer to an oven dish and grate over the remaining cheese.
Bake in the oven for 25 minutes or until dark golden and very thick, Season to perfection then serve drizzled with extra virgin olive oil.
