Cut the asparagus into 1-inch pieces and set aside (reserve a few tips for garnish see note below).
In a soup pot, melt the butter over medium heat, when it begins to foam add the garlic and cook for 30 seconds. Add the stock and asparagus, bring to a simmer. Cook for about 5 minutes, until the asparagus is tender, but still green.
When the asparagus is ready, remove from heat and puree using an immersion or regular blender. Pour back into the pot.
Add the cream and cook on low until heated through. Season to taste with salt and cayenne.
Ladle the asparagus soup into bowls and serve hot.
Cook's Note: If desired, blanch reserved asparagus tips to garnish top, along with an additional drizzle of cream.