- 1/2 cup unsalted butter, divided
- 3 tablespoons olive oil
- 1/4 cup diced white onion
- 8 ounces portobello mushrooms, stemmed and sliced
- 8 ounces baby bella mushrooms, sliced
- 8 ounces oyster mushrooms, sliced
- 1 1/2 teaspoons dried tarragon
- 3 (16 ounce) cans chicken broth
- 1 large baking potato, peeled and diced into small cubes
- 2 tablespoons fresh thyme
- 1 1/2 teaspoons dried oregano
- 1/2 cup heavy whipping cream (optional)
- salt and ground black pepper to taste
- Heat 1/4 cup butter and oil in a large pot over medium heat until butter melts, 1 to 2 minutes. Add onion; cook and stir until soft, about 5 minutes. Add remaining 1/4 cup butter, portobello mushrooms, baby bella mushrooms, and oyster mushrooms, and tarragon; cook and stir until tender, 5 to 7 minutes.
- Stir chicken broth, potato, thyme, and oregano into the pot. Bring to a boil; let soup simmer until potato is tender, 15 to 20 minutes.
- Remove soup from heat and puree with an immersion blender until smooth.
- Return soup to heat and simmer until heated through, about 5 minutes. Stir in heavy cream. Season with salt and pepper.