Preheat your oven to 375ºF (190ºC). Slice the tops off two heads of garlic, drizzle them with olive oil, and wrap them in foil. Place the wrapped garlic on a baking sheet and roast for about 40 minutes, until the cloves are soft and caramelized.

In a large pot, melt 4 tablespoons of salted butter over low-medium heat. Once melted, add one diced yellow onion and cook for about 5 minutes, stirring occasionally.

Sprinkle 1/4 cup of all-purpose flour over the sautéed onions, mixing thoroughly. Continue cooking for about 2 minutes.

Gradually pour in 4 cups of vegetable or chicken broth, followed by 2 cups of milk and 1 cup of half-and-half. Add 1 teaspoon of ground thyme, sea salt, and coarse black pepper to taste. Whisk and bring to a boil; reduce heat and let it simmer for about 5-7 minutes.

Peel and dice 2 large russet potatoes, then add them along with the squeezed roasted garlic cloves into the pot. Puree the mixture until completely smooth using a blender.

In a separate pan, heat a tablespoon of butter or olive oil over medium heat. Add 8 ounces of crimini mushrooms, cooking until nicely seared, about 5-6 minutes.

Stir the seared mushrooms into your creamy potato soup, allowing the flavors to meld for a few more minutes on low heat.

Ladle the steaming soup into bowls, garnishing with extra sautéed mushrooms, fresh thyme sprigs, and optional shredded cheese. Serve warm.