This is a kid favorite and it's full of vitamins. You can omit cream or use a dairy substitute if you like and use olive oil to make it vegan. It's all about developing the sweet flavors of the slow cooked onions that makes this soup so delicious. We used thyme from our garden to make it extra special. We also LOVE our stick blenders that make it much more safe and fun to cream soups, sauces and make things like smoothies. A great $40 investment.
¼ cup (½ stick) unsalted butter
10 sprigs thyme, tied together
1 medium onion, thinly sliced
2 garlic cloves, thinly sliced
¼ cup tomato paste
2 28-oz. cans whole tomatoes
1–2 teaspoons sugar, divided
¼ cup (or more) heavy cream
Kosher salt and freshly ground black pepper
Melt butter in a large heavy pot over medium heat. Add thyme, onion, and garlic. Cook until onion is completely soft and translucent, 10–12 minutes. Increase heat to medium-high; add tomato paste. Continue cooking, stirring often, until paste has begun to caramelize in spots, 5–6 minutes.
Add tomatoes with juices, 1 tsp. sugar, and 8 cups water to pot. Increase heat to high; bring to a simmer. Reduce heat to medium. Simmer until flavors meld and soup reduces to about 2 quarts (8 cups), 45–55 minutes. Remove soup from heat; let cool slightly. Discard thyme sprigs. Working in small batches, purée soup in a blender until smooth. Return to pot. DO AHEAD: Soup can be made 2 days ahead. Let cool slightly, cover, and chill. Rewarm before continuing.
Stir in ¼ cup cream. Simmer soup until flavors meld, 10–15 minutes longer. Season to taste with salt, pepper, and remaining 1 tsp. sugar. Add more cream, if desired.