Melt butter in a large heavy pot over medium heat. Add flour and minced garlic and season with salt and pepper. Stir well and add asparagus.
Keep stirring for 2-3 minutes until the vegetables begin to soften. You may add a cup of chicken stock at this stage. Then, add the rest of the stock and cook for another 3-4 minutes on medium flame.
Turn off the heat and let it cool before you transfer the asparagus mixture to a blender.
Pour the blended soup/puree in a heavy pot on medium flame and cook over medium heat.
Add milk with fresh cream. You may add another cup of milk if it is desired to get the right consistency and let it simmer on low flame for 1-2 minutes.
Add prawns and let it simmer for another minute or so. Save some prawns on the side to be added when serving the soup.
Season with salt, pepper and dry herbs.
Add the extra prawns and serve hot, garnished with fresh parsley leaves and toasted crusty bread on the side.
You can use fish stock for authentic seafood taste instead of chicken stock.