In a large pot, melt 2 tablespoons of butter with 1 tablespoon of olive oil over medium heat. Add 1 finely diced small onion and sauté for 3-4 minutes until translucent.

Stir in 2 minced garlic cloves and 1 teaspoon of fresh thyme leaves, cooking for an additional 1-2 minutes until fragrant.

Add 1 pound of sliced mushrooms, stirring well to combine. Cook for 8-10 minutes until softened and brown.

If preferred, sprinkle 1 tablespoon of all-purpose flour over the mixture, stir well to coat, and cook for 1 additional minute.

Pour in 4 cups of broth, bring to a gentle simmer, and allow to simmer for 10-15 minutes.

Use an immersion blender to purée the mixture to desired consistency, leaving some chunks if preferred.

Stir in 1 cup of heavy cream and warm through over low heat for 3-5 minutes. Adjust seasoning with salt and pepper.

Ladle soup into bowls, garnishing with freshly chopped parsley. Serve with crusty bread.