01 - Warm the butter and olive oil together in a large pot over medium heat.
02 - Add onion, carrot, and celery; cook for 5 minutes until softened.
03 - Stir in the minced garlic and cook for 1 minute until aromatic.
04 - Add sliced mushrooms and cook 8 to 10 minutes, stirring occasionally until juices are released and mushrooms begin to brown.
05 - Pour in the white wine if using and cook for 2 minutes until mostly evaporated.
06 - Incorporate thyme, bay leaf, salt, and pepper; stir to combine.
07 - Pour in vegetable broth, bring to a simmer, cover, and cook for 15 minutes.
08 - Remove bay leaf then blend soup until smooth using an immersion or countertop blender; return to pot.
09 - Stir in heavy cream and gently heat through; adjust seasoning to taste.
10 - Ladle into bowls and garnish with additional thyme and a drizzle of cream if desired; serve with crusty bread.