To make stock: heat olive oil and 1tbsp butter in a large pot. Add the onion, carrot, sprig of thyme, 1 tsp salt, 1/2 tsp pepper & cook over low heat for 10 - 15 minutes until vegetables are soft. Add 6 cups water & bring to a boil. Reduce heat & simmer uncovered for 30 minutes. Strain, reserving the liquid. There should be about 4 1/2 cups of stock. If not, add water.

Meanwhile in another large pot, heat remaining stick of butter and add leeks. Cook over low heat for 15 - 20 minutes until leeks begin to brown. Slice all mushrooms 1/4 inch thick or bite size pieces. Add sliced mushrooms and cook for 10 minutes or until tender. Add flour and cook for 1 minute. Add white wine and stir another minute scraping bottom of pot. Add vegetable stock, minded thyme, 1 1/2 tsp salt, 1 tsp pepper and bring to a boil. Reduce heat and simmer for 15 minutes. Add half & half, cream & parsley. Season with salt & pepper to taste & heat through but do not boil. Serve hot.