Preheat oven to 450 degrees and line a baking sheet.

Toss the quartered bell peppers, sliced onion, and whole garlic cloves in 2 tbsp of avocado oil until well coated. Place the vegetables in a single layer (peppers with skin side up) on the prepared baking sheet and bake for 18 minutes. Turn the oven up to broil and broil for 2 minutes.

Meanwhile, heat the remaining 2 tbsp oil in a large Dutch oven or pot over medium heat. Add the carrots and celery and cook 5-6 minutes, until the vegetables are softened. Add the basil leaves and cook another 1 minute until the basil is fragrant.

Add the vegetable broth, crushed tomatoes, Italian seasoning, salt, and pepper and bring the mixture to a boil. Once boiling, add the roasted vegetables and garlic to the pot and boil for 5 minutes.

Using a blender, food processor, or immersion blender, blend the soup until smooth. Return the soup to the pot, and stir in the heavy cream and thyme leaves. Serve!