How to Make It
In a blender, combine the arugula with the basil, garlic, butter, thyme, oregano and rosemary and pulse until finely chopped. Add 1/4 cup of the vegetable stock and puree until smooth. Transfer the puree to a large saucepan and stir in the remaining 3 3/4 cups of vegetable stock. Bring to a simmer over moderately low heat and season with salt and pepper.
Rinse out the blender. Add the Parmesan and milk and puree until smooth. Transfer the cream to a small heatproof bowl set over a small saucepan of simmering water and stir until warm, about 2 minutes. Ladle the soup into plates and serve with a swirl of Parmesan cream.