Ingredients:

  • 4 tbsp unsalted butter
  • 1 medium yellow onion, finely diced
  • 4 cloves garlic, minced
  • 1 lb cremini mushrooms, sliced
  • 1/2 lb shiitake mushrooms, sliced
  • 1 tsp dried thyme
  • 1 bay leaf
  • 1/4 cup all-purpose flour
  • 6 cups low-sodium vegetable broth
  • 1 tsp salt
  • 1/2 tsp cracked black pepper
  • 1 cup heavy cream
  • 1 tbsp fresh lemon juice
  • 2 tbsp fresh parsley, chopped

Instructions:

  1. Heat 4 tbsp unsalted butter in a large skillet over medium-high heat. Add the diced yellow onion and cook for 5–7 minutes until translucent and soft.
  2. Stir in the sliced cremini and shiitake mushrooms; cook undisturbed for 3–5 minutes to develop a deep brown sear, then stir and cook for another 5 minutes until the moisture has evaporated and the mushrooms are dark golden.
  3. Add the minced garlic and dried thyme, stirring for 60 seconds until fragrant.
  4. Sprinkle 1/4 cup all-purpose flour over the mushroom mixture and stir constantly for 2 minutes to cook out the raw flour taste.
  5. Transfer the mushroom mixture into the slow cooker. Pour in 6 cups low-sodium vegetable broth, a splash of lemon juice, and add the bay leaf, 1 tsp salt, and 1/2 tsp cracked black pepper. Stir well to combine.
  6. Cover and cook on High for 4 hours or Low for 8 hours.
  7. Turn the slow cooker to Low. Stir in 1 cup heavy cream and the remaining fresh lemon juice. Let the soup warm through for 10–15 minutes, leaving the lid slightly ajar if a thicker consistency is desired.
  8. Remove the bay leaf. Taste and adjust salt and pepper if needed.
  9. Optional: Use an immersion blender to pulse the soup 3–4 times to release mushroom starches without pureeing the entire batch.
  10. Stir in 2 tbsp chopped fresh parsley just before serving.