Toss mushrooms with onion, garlic, and oil. Season with salt, pepper, thyme, and sage. Spread on baking sheet. Roast for 10 minutes, remove from oven and turn the vegetables. Continue roasting for additional 15 minutes.
Prepare a soup pot with broth, beans, salt, and pepper. Turn heat to medium and simmer.
Add the roasted vegetables to your pot.
Remove 2 cups of the white beans, and 1 cup of broth from the stock pot.
Using a blender, blend the 2 cups of beans and 1 cup of water until creamy.
Add pureed bean mixture back to soup and mix with a whisk until the broth becomes creamy and smooth.
Garnish with sautéed shiitake mushrooms and parsley. Enjoy!