Sauté Aromatics: In a large pot, melt butter over medium heat. Add chopped onion and minced garlic, sautéing until translucent (3-4 minutes).
Add Vegetables: Stir in mixed vegetables and cook for 5 minutes.
Simmer: Pour in vegetable broth, thyme, salt, and pepper. Bring to a boil, then reduce heat and simmer for 15 minutes or until vegetables are tender.
Blend: Remove from heat. Use an immersion blender to purée until smooth (or transfer to a blender in batches).
Creamy Finish: Return soup to low heat, stir in heavy cream, and warm through (do not boil).
Garnish & Serve: Ladle into bowls, top with fresh parsley, and enjoy with crusty bread!