- 1/4 cup butter
- 1/2 onion, diced
- 2 cups fresh mushrooms, sliced
- 1/4 cup all-purpose flour
- 1 quart cold beef stock
- 1 cup heavy whipping cream
- 1 tablespoon chopped fresh flat-leaf parsley
- salt and freshly ground black pepper to taste
- Melt butter in a soup pot over medium heat. Cook and stir onion in the melted butter until golden brown, about 7 minutes. Add mushrooms to the onion mixture; cook and stir until softened, 5 to 8 minutes.
- Sprinkle flour over the mushroom mixture and stir until no longer lumpy and aromatic, 2 to 3 minutes. Slowly pour beef broth over mushroom mixture and stir to combine. Bring broth to a boil and reduce heat to medium-low. Simmer mushroom mixture, stirring frequently, until thickened, 2 to 3 minutes.
- Pour the cream into the mushroom mixture and cook until soup is thickened, 5 to 10 minutes more. Stir parsley into soup.