Preheat oven to 400 degrees.
Roast heads of garlic (see How To link in post).
Large cube bread and spread on baking sheet. Toast in oven for 10-15 minutes, until slightly crispy. Reserve 1 cup of toasted cubes for serving.
While garlic roasts, melt butter in a large skillet over medium heat, sauté mushrooms until browned nicely on both sides. Do not overcrowd pan. Work in batches if necessary. Reserve.
In a soup pot, sauté shallot in 1 Tbl. olive oil until tender, add in thyme sprigs, chicken broth; bring to a simmer over medium heat for 5 minutes. Reduce to low; remove thyme, stir in cream, roasted garlic and toasted bread (less reserved one cup).
Fold to combine, then puree lightly. Season with salt & pepper to taste.
To serve, sprinkle with freshly grated parmesan cheese, sautéed mushrooms & reserved toasted bread cubes.