This soup is delicious!
Heat olive oil in a stockpot over medium heat. Cook and stir onion in hot oil until softened, about 5 minutes.
Stir garlic through the onion; cook and stir until garlic is fragrant and slightly soft, another 1 to 2 minutes.
Place broccoli, diced tomatoes, and chicken broth into the stockpot. Reduce heat to medium-low, bring the mixture to a simmer, and cook until the broccoli is completely softened, 30 to 40 minutes.
Stir milk into the soup and return to a simmer.
Pour the soup into a blender, filling the pitcher no more than halfway. Hold the lid of the blender firmly in place and carefully start the blender, using a few quick pulses to get the soup moving before leaving it on to puree. Puree in batches until smooth and pour into a serving dish. Season with salt and black pepper to serve.
Per Serving: 100 calories; protein 4.7g; carbohydrates 13.7g; fat 2.9g; cholesterol 2.6mg; sodium 588.9mg.