Heat olive oil and saute garlic and onion in a large soup pot over medium heat, until onion is translucent (roughly five minutes).
Add tomatoes with juice and chicken broth, bringing to a boil. Reduce heat and simmer 20 minutes, or until soup begins to thicken. Add basil, stirring to combine.
If you prefer tomato soup smooth, transfer to a food processor and blend until smooth then return to pot, otherwise skip this step. Stir in milk.
You can serve now or allow to cool and transfer to labelled freezer containers in your preferred serving size.