Heat olive oil in a large pot.

Add sliced mushrooms, chopped onion, minced garlic, and crushed dried thyme to the pot.

Sauté the vegetables and thyme, stirring often, for about 7 minutes, or until the onion is tender and the mushrooms are slightly golden.

Pour chicken broth, stewed tomatoes (with liquid), and dry white wine into the pot.

Bring the mixture to a boil.

Reduce heat to low, cover the pot, and let the stew simmer for 15 minutes.

In a separate bowl, mash 1 cup of cannellini beans until smooth using a potato masher.

Add the mashed beans to the stew pot.

Add the remaining (unmashed) cannellini beans to the pot.

Stir the stew to combine all ingredients thoroughly.

Cook the stew until it is heated through.

Season with salt and pepper to taste, if desired.

Serve hot, optionally with steamed rice and garnished with fresh thyme sprigs.