How to Make It
Preheat oven to 375°F. Place tomatoes (cut side down), onion, fennel, carrot, and garlic cloves on a half-size (18- x 13- x 1-inch) rimmed baking sheet coated with cooking spray. Stir together oil and tomato paste in a small bowl. Add oil mixture, thyme, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper to tomato mixture; toss to coat. Bake in preheated oven until vegetables are tender and beginning to brown, about 35 minutes.
Squeeze garlic from cloves into a blender; discard skins. Scrape vegetable mixture and any accumulated pan juices into blender.
Combine stock and cream in a large microwavable bowl; microwave on HIGH until hot, 2 to 3 minutes. Add stock mixture, vinegar, and remaining 1/2 teaspoon salt and 1/4 teaspoon pepper to blender. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Process until very smooth, 30 seconds to 1 minute.
Carefully pour soup into 4 bowls; top servings evenly with parsley.