Roasted Vegetable Broth

1 cup quartered crimini mushroom s

1 cup sliced carrot s

1/2 cup chopped parsnip s

1/2 cup sliced celery

4 large garlic cloves, crushed, peeled

1 tablespoon olive oil

8 cups water

1 cup coarsely chopped Swiss chard (including stems)

1/2 cup thinly sliced leek (white and pale green parts only)

1/4 cup chopped fresh parsley (including stems)

1 teaspoon salt

1 bay leaf

1 large fresh thyme sprig or 1/2 teaspoon dried thyme