Heat the olive oil in a small saucepan over medium.
Add the mushrooms and shallots and sauté for 10 minutes or until softened and browned.
Add the thyme and sauté for a further minute.
Add the flour and cook stirring constantly for 5 minutes or until golden brown.
Whisk in the stock in a steady stream until it reaches a smooth consistency. add the porcini mushrooms and simmer for 3 minutes to thicken and then stir in the salt and pepper.