Clean the mushrooms by wiping them off with a dry paper towel. Don’t wash them! Slice the mushrooms or chop them into bite-sized pieces. Set aside.
Heat 1 tablespoon of the olive oil in a large pot. Once oil is hot add the mushrooms and thyme and cook for 10 minutes or until lightly browned. Place in a bowl and set aside.
Remove thyme stems (leaves should have fallen off)
In the same pot, heat the remaining 1 tablespoon of olive oil then add the onions.
Cook covered over low heat, stirring occasionally for 15 minutes. Then add the mushrooms back into the pot.
Next, add the butter. Allow it to melt then add the flour and cook for 1 minute. Add the vegetable stock and stir for another minute, scraping the bottom of the pot.
Add the salt and pepper pepper and bring to a boil. Reduce heat to a simmer and simmer for 15 minutes.
Then add the half-and-half, cream and parsley. Heat through but do not boil. Season with additional salt and pepper, to taste. Serve hot.