Chop up the whole head of broccoli (yes, leaves and stems too!) into bite-sized chunks.
Heat oil in a large dutch oven, add onion and garlic and sauté until translucent, about three minutes.
Add broccoli and sauté for about a minute. Add stock to cover all the veggie goodness, cover and bring to a boil. Reduce to simmer for 20 minutes or until broccoli is tender. Add thyme and rosemary.
Drop in your immersion blender once cooled and puree to preferred consistency (we like to leave a couple of chunks for texture). Add in milk as desired.