Combine cheese and thyme; set aside. Finely chop 2 containers portobello mushrooms (12 ounces); chop remaining container portobello mushrooms into bigger pieces. In large diameter skillet or Dutch oven, heat olive oil. Saute shallots and leek over medium heat until softened (about 5 minutes), stirring often. Stir finely chopped mushrooms into shallots and leek; saute until tender (about 10 minutes). Reduce heat, stir in wine; simmer 5 minutes. Stir in flour until smooth. Slowly pour in chicken broth; stir in larger mushroom pieces. Bring to a boil, stirring constantly; boil 1 minute. Stir in cream, salt and pepper; heat through. Spoon into soup bowls; garnish with cheese.