Preheat the oven to 400°F. Place the tomatoes and garlic on a baking sheet lined with aluminum foil. Drizzle on the olive oil and sprinkle with salt and pepper. Stir with a large spoon or your hands to ensure everything is coated. Roast for 30 minutes and then remove from the oven and set aside.
Place the butter in a large heavy-bottomed pot like a dutch oven or stockpot. Melt the butter over medium-high heat and then add the onions. Cook the onions until translucent and just starting to brown, about 10 minutes.
Add the chicken stock, basil, and oregano to the onions. Carefully add the roasted tomatoes and garlic along with all of the juices to the pot as well and stir to combine. Add in the baking soda and continue stirring. The mixture will bubble up for a moment, and then settle. After the mixture has come to a boil, reduce the heat and simmer uncovered for 30 minutes.
Pour the soup into a blender (or use your immersion/hand blender) and purée it until nice and smooth. You may need to do this in batches depending on the size of your blender. Be careful on this step because the soup is HOT!
Return the soup to the saucepan over low heat and stir in the heavy cream. Bring the soup back to a simmer while stirring, you don't want it to boil. Taste for seasoning and add any salt or pepper if needed.
Serve in bowls and garnish as desired. Enjoy!
This recipe will make about 10 cups of soup.
Baking soda is added to tomato soup to neutralize the acid in the tomatoes. Baking soda also helps when adding milk or cream to a soup. The dairy will not curdle if there is baking soda in the soup.
Store this soup in a sealable container in the fridge for 3-4 days. Or, you can freeze this soup in a freezer-safe container for up to 6 months. Just make sure the soup has completely cooled before freezing and you leave room for the soup to expand in the container.
Instead of cooking the onions in butter, you can use your favorite cooking oil like olive oil or coconut oil. And, if you are really looking to cut calories, skip the cream or substitute it with Greek yogurt or low-fat milk instead.