In a large pot, melt 4 tablespoons of butter and add 1 tablespoon of oil over medium-high heat. Once the butter is bubbling, toss in 2 cups of diced onions and cook for 2-3 minutes until they soften and become translucent. Add 4 minced garlic cloves and stir for another minute until fragrant.

Add 1 ½ pounds of sliced brown mushrooms and half of the 4 teaspoons of chopped thyme to the pot. Allow the mushrooms to sauté undisturbed for about 5-7 minutes until they sauté down, releasing moisture and beginning to brown.

Pour in ½ cup of Marsala wine, scraping the bottom of the pot with a wooden spoon to lift the browned bits. Let the wine simmer briefly until the alcohol evaporates.

Sprinkle 6 tablespoons of flour evenly over the mushroom mixture, stirring until well coated. Cook for approximately 2 minutes, ensuring the flour has a chance to toast slightly.

Slowly add 4 cups of low-sodium chicken broth while stirring constantly to avoid lumps. Bring the mixture to a boil, then reduce the heat to a simmer. Season with 1-2 teaspoons of salt, ½-1 teaspoon of cracked black pepper, and the crumbled beef bouillon cubes.

Cover your pot and let the soup simmer for 10-15 minutes, stirring occasionally. This will allow the soup to thicken and the flavors to meld together beautifully.

Lower the heat and gently stir in 1 cup of heavy cream or half and half, ensuring not to boil.

Ladle the soup into bowls, stirring in the remaining thyme and garnishing with ½ tablespoon of chopped parsley on top.