Trim the woody ends off the 3 pounds Asparagus spears and cut the spears into 1-inch pieces. Reserve a handful of tips for garnish, if desired.
In a large soup pot, melt the 4 tablespoons Butter over medium heat. Add the chopped 2 medium Onion and 4 cloves Garlic , cooking for 3–4 minutes until softened and fragrant.
Add the asparagus pieces (excluding the reserved tips) and sauté for 2–3 minutes. Pour in the 8 cups Chicken stock or vegetable stock, bring to a boil, then reduce the heat. Cover and simmer for 10–12 minutes, or until the asparagus is tender.
Use an immersion blender to blend the soup until smooth and velvety. (Alternatively, carefully transfer in batches to a countertop blender.)
Stir in the 2 cups Heavy cream , then season with 2 teaspoons Salt and freshly 1 teaspoon Black Pepper to taste. Warm gently over low heat, being careful not to let it boil.
Ladle the soup into bowls, top with reserved asparagus tips and fresh herbs if desired, and serve warm alongside crusty bread or a light salad.